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The 4 GMAT Math Strategies Everyone Must Master: Testing Cas [#permalink]
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FROM Manhattan GMAT Blog: The 4 GMAT Math Strategies Everyone Must Master: Testing Cases Redux

A while back, we talked about the 4 GMAT math strategies that everyone needs to master. Today, I’ve got some additional practice for you with regard to one of those strategies: Testing Cases.

Try this GMATPrep® problem:

* ” If xy + z = x(y + z), which of the following must be true?

“(A) x = 0 and z = 0

“(B) x = 1 and y = 1

“(C) y = 1 and z = 0

“(D) x = 1 or y = 0

“(E) x = 1 or z = 0

How did it go?

This question is called a “theory” question: there are just variables, no real numbers, and the answer depends on some characteristic of a category of numbers, not a specific number or set of numbers. Problem solving theory questions also usually ask what must or could be true (or what must not be true). When we have these kinds of questions, we can use theory to solve—but that can get very confusing very quickly. Testing real numbers to “prove” the theory to yourself will make the work easier.

The question stem contains a given equation:

xy + z = x(y + z)

Whenever the problem gives you a complicated equation, make your life easier: try to simplify the equation before you do any more work.

xy + z = x(y + z)

xy + z = xy + xz

z =  xz

Very interesting! The y term subtracts completely out of the equation. What is the significance of that piece of info?

Nothing absolutely has to be true about the variable y. Glance at your answers. You can cross off (B), (C), and (D) right now!

Next, notice something. I stopped at z = xz. I didn’t divide both sides by z. Why?

In general, never divide by a variable unless you know that the variable does not equal zero. Dividing by zero is an “illegal” move in algebra—and it will cause you to lose a possible solution to the equation, increasing your chances of answering the problem incorrectly.

The best way to finish off this problem is to test possible cases. Notice a couple of things about the answers. First, they give you very specific possibilities to test; you don’t even have to come up with your own numbers to try. Second, answer (A) says that both pieces must be true (“and”) while answer (E) says “or.” Keep that in mind while working through the rest of the problem.

z =  xz

Let’s see. z = 0 would make this equation true, so that is one possibility. This shows up in both remaining answers.

If x = 0, then the right-hand side would become 0. In that case, z would also have to be 0 in order for the equation to be true. That matches answer (A).

If x = 1, then it doesn’t matter what z is; the equation will still be true. That matches answer (E).

Wait a second—what’s going on? Both answers can’t be correct.

Be careful about how you test cases. The question asks what MUST be true. Go back to the starting point that worked for both answers: z = 0.

It’s true that, for example, 0 = (3)(0).

Does z always have to equal 0? Can you come up with a case where z does not equal 0 but the equation is still true?

Try 2 = (1)(2). In this case, z = 2 and x = 1, and the equation is true. Here’s the key to the “and” vs. “or” language. If z = 0, then the equation is always 0 = 0, but if not, then x must be 1; in that case, the equation is z = z. In other words, either x = 1 OR z = 0.

The correct answer is (E).

The above reasoning also proves why answer (A) could be true but doesn’t always have to be true. If both variables are 0, then the equation works, but other combinations are also possible, such as z = 2 and x = 1.

Key Takeaways: Test Cases on Theory Problems

(1) If you didn’t simplify the original equation, and so didn’t know that y didn’t matter, then you still could’ve tested real numbers to narrow down the answers, but it would’ve taken longer. Whenever possible, simplify the given information to make your work easier.

(2) Must Be True problems are usually theory problems. Test some real numbers to help yourself understand the theory and knock out answers. Where possible, use the answer choices to help you decide what to test.

(3) Be careful about how you test those cases! On a must be true question, some or all of the wrong answers could be true some of the time; you’ll need to figure out how to test the cases in such a way that you figure out what must be true all the time, not just what could be true.

 

* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.
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Re: The 4 Math Strategies Everyone Must Master: Testing Cases Re [#permalink]
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FROM Manhattan GMAT Blog: The 4 Math Strategies Everyone Must Master: Testing Cases Redux

A while back, we talked about the 4 math strategies that everyone needs to master. Today, I’ve got some additional practice for you with regard to one of those strategies: Testing Cases.

Try this GMATPrep® problem:

* ” If xy + z = x(y + z), which of the following must be true?

“(A) x = 0 and z = 0

“(B) x = 1 and y = 1

“(C) y = 1 and z = 0

“(D) x = 1 or y = 0

“(E) x = 1 or z = 0

How did it go?

This question is called a “theory” question: there are just variables, no real numbers, and the answer depends on some characteristic of a category of numbers, not a specific number or set of numbers. Problem solving theory questions also usually ask what must or could be true (or what must not be true). When we have these kinds of questions, we can use theory to solve—but that can get very confusing very quickly. Testing real numbers to “prove” the theory to yourself will make the work easier.

The question stem contains a given equation:

xy + z = x(y + z)

Whenever the problem gives you a complicated equation, make your life easier: try to simplify the equation before you do any more work.

xy + z = x(y + z)

xy + z = xy + xz

z =  xz

Very interesting! The y term subtracts completely out of the equation. What is the significance of that piece of info?

Nothing absolutely has to be true about the variable y. Glance at your answers. You can cross off (B), (C), and (D) right now!

Next, notice something. I stopped at z = xz. I didn’t divide both sides by z. Why?

In general, never divide by a variable unless you know that the variable does not equal zero. Dividing by zero is an “illegal” move in algebra—and it will cause you to lose a possible solution to the equation, increasing your chances of answering the problem incorrectly.

The best way to finish off this problem is to test possible cases. Notice a couple of things about the answers. First, they give you very specific possibilities to test; you don’t even have to come up with your own numbers to try. Second, answer (A) says that both pieces must be true (“and”) while answer (E) says “or.” Keep that in mind while working through the rest of the problem.

z =  xz

Let’s see. z = 0 would make this equation true, so that is one possibility. This shows up in both remaining answers.

If x = 0, then the right-hand side would become 0. In that case, z would also have to be 0 in order for the equation to be true. That matches answer (A).

If x = 1, then it doesn’t matter what z is; the equation will still be true. That matches answer (E).

Wait a second—what’s going on? Both answers can’t be correct.

Be careful about how you test cases. The question asks what MUST be true. Go back to the starting point that worked for both answers: z = 0.

It’s true that, for example, 0 = (3)(0).

Does z always have to equal 0? Can you come up with a case where z does not equal 0 but the equation is still true?

Try 2 = (1)(2). In this case, z = 2 and x = 1, and the equation is true. Here’s the key to the “and” vs. “or” language. If z = 0, then the equation is always 0 = 0, but if not, then x must be 1; in that case, the equation is z = z. In other words, either x = 1 OR z = 0.

The correct answer is (E).

The above reasoning also proves why answer (A) could be true but doesn’t always have to be true. If both variables are 0, then the equation works, but other combinations are also possible, such as z = 2 and x = 1.

Key Takeaways: Test Cases on Theory Problems

(1) If you didn’t simplify the original equation, and so didn’t know that y didn’t matter, then you still could’ve tested real numbers to narrow down the answers, but it would’ve taken longer. Whenever possible, simplify the given information to make your work easier.

(2) Must Be True problems are usually theory problems. Test some real numbers to help yourself understand the theory and knock out answers. Where possible, use the answer choices to help you decide what to test.

(3) Be careful about how you test those cases! On a must be true question, some or all of the wrong answers could be true some of the time; you’ll need to figure out how to test the cases in such a way that you figure out what must be true all the time, not just what could be true.

 

* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.
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why not jsut shift z to the other size
i.e xz - z = 0
z(x-1)=0
Therefore, either z=0 or x - 1 = 0
i.e z=0 or x=1 Ans)E
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Open House – Earn $100/hr Teaching with Manhattan Prep [#permalink]
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FROM Manhattan GMAT Blog: Open House – Earn $100/hr Teaching with Manhattan Prep


Please join us for an exciting, online open house to learn about the rewarding teaching opportunities with Manhattan Prep.

We are seeking expert teachers throughout the US who have proven their mastery of the GMAT, GRE or LSAT and who can engage students of all ability levels. Our instructors teach in classroom and one-on-one settings, both in-person and online. We provide extensive, paid training and a full suite of print and digital instructional materials. Moreover, we encourage the development and expression of unique teaching styles..

All Manhattan Prep instructors earn $100/hour for teaching and tutoring – up to four times the industry standard.  These are part-time positions with flexible hours. Many of our instructors maintain full-time positions, engage in entrepreneurial endeavors, or pursue advanced degrees concurrently while teaching for Manhattan Prep.  (To learn more about our exceptional instructors, read their bios or view this short video.

Learn about how to transform your passion for teaching into a lucrative and fulfilling part-time career by joining us for this Online Open House event!

To attend this free event, please select from one of the following online events and follow the on-screen instructions:

Wednesday, 5/21 from 9 – 10pm ET

To teach at Manhattan LSAT:

https://www.manhattanlsat.com/EventShow.cfm?EID=3&eventID=1373

To teach at Manhattan GMAT:

https://www.manhattangmat.com/classes/details/13789

To teach at Manhattan GRE:

https://www.manhattanprep.com/gre/EventShow.cfm?EID=3&eventID=751

Sunday, 6/22 from 8 – 9pm ET

To teach at Manhattan LSAT:

https://www.manhattanlsat.com/EventShow.cfm?EID=3&eventID=1374

To teach at Manhattan GMAT:

https://www.manhattangmat.com/classes/details/13792

To teach at Manhattan GRE:

https://www.manhattanprep.com/gre/EventShow.cfm?EID=3&eventID=752

About Manhattan Prep

Manhattan Prep is a premier test-preparation company serving students and young professionals studying for the GMAT (business school), LSAT (law school), GRE (master’s and PhD programs), and SAT (undergraduate programs).  We are the leading provider of GMAT prep in the world.

Manhattan Prep conducts in-person classes and private instruction across the United States, Canada, and England.  Our online courses are available worldwide, and our acclaimed Strategy Guides are available at Barnes & Noble and Amazon.  In addition, Manhattan Prep serves an impressive roster of corporate clients, including many Fortune 500 companies.  For more information, visit www.manhattanprep.com.
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What’s the deal with Integrated Reasoning? [#permalink]
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FROM Manhattan GMAT Blog: What’s the deal with Integrated Reasoning?


Integrated Reasoning, the newest addition to the GMAT, was added to the GMAT in response to real skills employers are looking for in new hires – namely, the ability to analyze information presented in multiple ways – in order to succeed in today’s data-driven workplace. Sounds tough, right? The good news is that Integrated Reasoning can be learned.

And we’ve created a new tool to teach it—available for free for a limited time only!



The complete GMAT INTERACT platform (coming in June!) will teach every section of the GMAT, but you can get started on the IR section right now, for free. It won’t be available for free forever, though, so be sure to sign up before it’s too late!

Are you ready to learn Integrated Reasoning? Try GMAT INTERACT for Integrated Reasoning for free here.
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Geometry – Who Said Geometry? It’s Algebra! [#permalink]
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FROM Manhattan GMAT Blog: Geometry – Who Said Geometry? It’s Algebra!

The GMAT quant section has many faces – there are a number of content areas, and it is best to try to master as many of them as you can before test day. It is important, however, that you not compartmentalize too much. In many of the harder questions in fact, two or more topics often show up together. You can easily find quadratics in a consecutive integer question, coordinate geometry in a probability question, number properties in a function question, for example. One common intersection of two topics that I find surprises many students is that of geometry and algebra. Many people expect a geometry question to be about marking up diagrams with values or tick marks to show equality and/or applying properties and formulas to calculate or solve. While these are no doubt important skill sets in geometry, don’t forget to pull out one of the most important skills from your  GMAT tool bag – the almighty variable! x’s and y’s have a welcomed home in many a geometry question, though you might find that you are the one who has to take the initiative to put them there!

Take a look at this data sufficiency question from GMATPrep®



In the figure shown, the measure of
PRS is how many degrees greater than the measure of
PQR?

(1) The measure of
QPR is 30 degrees.

(2) The sum of the measures of
 PQR and
PRQ is 150 degrees.

How did you do? Don’t feel bad if you’re a little lost on this one. This is a difficult question, though you’ll see that with the right moves it is quite doable. At the end of this discussion, you’ll even see how you could put up a good guess on this one.

As is so often the case in a data sufficiency question, the right moves here start with the stem – in rephrasing the question. Unfortunately the stem doesn’t appear to provide us with a lot of given information. As indicated in the picture, you have a 90 degree angle at
 PQR and that seems like all that you are given, but it’s not! There are some other inherent RELATIONSHIPS, ones that are implied by the picture. For example
PRS and
PRQ sum to 180 degrees. The problem, however, is how do you CAPTURE THOSE RELATIONSHIPS? The answer is simple – you capture those relationships the way you always capture relationships in math when the relationship is between two unknown quantities – you use variables!

But where should you put the variables and how many variables should you use?  This last question is one that you’ll likely find yourself pondering  a number of times on the GMAT. Some believe the answer to be a matter of taste. My thoughts are always use as few variables as possible. If you can capture all of the relationships that you want to capture with one variable, great. If you need two variables, so be it. The use of three or more variables would be rather uncommon in a geometry question, though you could easily see that in a word problem.  Keep one thing in mind when assigning variables: the more variables you use, usually the more equations you will need to write in order to solve.

As for the first question above about where to place the variables, you can take a closer look in this question at what they are asking and use that as a guide. They ask for the   (degree) difference between
PRS and
PQR. Since
PRS is in the question, start by labeling
PRS as x. Since
PRS and
 PRQ sum to 180 degrees, you can also label
PRQ as (180 – x) and
 RPS as (180 – x – 90) or (90 – x).

Can you continue to label the other angles in triangle PRQ in terms of x or is it now time to place a second variable, y? Since you still have two other unknown quantities in that triangle, it’s in fact time for that y. The logical place of where to put it is on
 PQR since that is also part of the actual question. The temptation is to stop there – DON’T! Continue to label the final angle of the triangle,
QPR, using your newfound companions, x and y.
QPR can be labeled as [180 – y – (180 – x)] or (x – y). Now all of the angles in the triangle are labeled and you are poised and ready to craft an algebraic equation/expression to capture any other relationships that might come your way.



Before you rush off to the statements, however, there is one last step. Formulate what the question is really asking in terms of x and y. The question rephrases to “What is the value of x – y?”

Now you can finally head to the statements. Oh the joy of a fully dissected data sufficiency stem – 90% of the work has already been done!

Statement (1) tells you that the measure of
QPR is 30 degrees. Using your x – y expression from the newly labeled diagram as the value of
 QPR, you can jot down the equation x – y = 30. Mission accomplished! The statement is sufficient to answer the question “what is the value of x – y?”

Statement (2) indirectly provides the same information as statement (1). If the two other angles of triangle PQR sum to 150 degrees, then
QPR is 30 degrees, so the statement is sufficient as well. If you somehow missed this inference and instead directly pulled from the diagram y + (180 – x) and set that equal to 150, you’d come to the same conclusion. Either way the algebra saves the day!

The answer to the question is D, EACH statement ALONE is sufficient to answer the question asked.

NOTE here that from a strategic guessing point of view, noticing that statements (1) and (2) essentially provide the same information allows you to eliminate answer choices A, B and C: A and B because how could it be one and not the other if they are the same, and C because there is nothing gained by combining them if they provide exactly the same information.

The takeaways from this question are as follows:

(1) When a geometry question has you staring at the diagram, uncertain of how to proceed in marking things up or capturing relationships that you know exist – use variables! Those variables will help you move through the relationships just as actual values would.

(2) In data sufficiency geometry questions, when possible represent the question in algebraic form so the target becomes clear and so that the rules of algebra are there to help you assess sufficiency.

(3) Once you have assigned a variable, continue to label as much of the diagram in terms of that variable. If you need a second variable to fully label the diagram, use it. If you can get away with just one variable and still accomplish the mission, do so.

Most GMAT test-takers know that they need to develop clear strategies when it comes to different types of word problems, and most of those involve either muscling your way through the problem with some kind of practical approach (picking numbers, visualizing, back-solving, logical reasoning) or writing out algebraic equations and solving.  There are of course pluses and minuses to all of the approaches and those need to be weighed by each person on an individual basis. What few realize, however, is that geometry questions can also demonstrate that level of complexity and thus can often also be solved with the tools of algebra. When actual values are few and far between, don’t hesitate to pull out an “x” (and possibly also a “y”) and see what kind of equations/expressions you can cook up.

For more practice in “algebrating” a geometry question, please see OG 13th DS 79 and Quant Supplement 2nd editions PS 157, 162 and DS 60, 114 and 123.

 
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The Distinction between a 700 and a 760 [#permalink]
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FROM Manhattan GMAT Blog: The Distinction between a 700 and a 760

I first wrote about this topic back in 2010. I’ve seen so many people lately on the forums who are going for a 750 or 760+ that I decided to revive the conversation.

My first version of this article started out with some reservations about this topic—and those reservations haven’t gone away. In fact, they’ve grown a little. Just yesterday, I answered a forum question from someone who told me that his or her desired school required a 750 or higher.

I don’t know a single school that says it requires a 750 or higher—and if there is one, then that admissions team is using the test incorrectly and people should be skeptical about attending that school. As far as the GMAT can tell, someone scoring 720 and someone scoring 750 are both equally capable of performing well at any particular business school. (Other reasons may exist for preferring one person over the other, but the GMAT is not one of those reasons.)

Second of all, I talk to many people on the forums who set a goal score and just assume that, as long as they study hard enough, they can get that score. In fact, they think there’s something wrong with them when they struggle to get there. The GMAT is not a static school test, where everyone could theoretically score the top score if they just studied enough. By definition, only 1 percent of test-takers will score 760 or higher.

That loops us back around to my first concern: given that so few people achieve these scores, any school that required a 750 or 760 (or higher) would not have very many candidates to choose from among when building its next MBA class. In addition, the school would build a very lopsided class. The GMAT is one admissions tool, but only one. There are many very strong candidates who do not hit the top level on this particular piece of the admissions puzzle.

In short, most people going for this kind of crazy-high score would be far better off using that time to work towards a promotion at work, or volunteer, or spend more time with family and friends. That is, unless you want to teach for my company—we’re the only organization I know that actually does require a 760+.

I also have to discuss something about the ranges I’ve chosen, 700 versus 760. You receive quant and verbal sub-scores on the GMAT, which are combined into a three digit score. The sub-scores can be quite different (or pretty similar) to get a 700 (or any score).

This article will assume that the sub-scores are roughly similar (that is, the person does not have a big disparity between the two sub-scores). If such a disparity does exist—for example, a 70th percentile quant score and a 95th percentile verbal score—then that person may score a 700, but will not have mastered everything listed below for the quant portion. At the same time, that person will likely have mastered many, if not most, things listed under the “760-level” section below for the verbal portion.

Mastery
Before we can dive into what mastery means for each of these two groups, we have to define something: what it means to recognize what to do on a problem. If you recognize what to do, then when you see a new question, you quickly (within about 20 to 30 seconds) make a connection to some problem you’ve done in the past; there’s some similarity between the two problems and you recognize that similarity.

As a result of that recognition, you now know what to do in order to solve this problem, because you can use the same (or a very similar) solution method. You will also be aware of the common mistakes you might make or traps you might fall into on a question like this one. You may save a little time and you’re more likely to answer the problem correctly.

By contrast, if you don’t recognize what to do, you have to figure out what to do “from scratch” (from the beginning); that slows you down and doesn’t give you any advantage in terms of accuracy.

Okay, here are the differences in mastery for 700-level and 760-level scorers:



What jumped out at you? I’d like to point out a few important points.

First, even at the 760+ level, you won’t recognize what to do with everything. You also do have to guess, even at the highest levels.

Second, the key difference is that those capable of scoring 760+ are able to recognize what to do on large portions of the test. This does not mean that they’ve seen that exact problem (or a close one) with different words or numbers.

Rather, it means that they recognize the type of reasoning used or the type of trap set or something about the way the problem was put together. They may still have to adapt to some kind of unexpected twist—but they have a much better chance of doing so successfully in the limited available time because they recognize the underlying structure of the problem.

Read this article about Decoding the Prime Disguise for an example. Note that the beginning of the article has a link to a prior article—follow the link and read the older article first. Try the two problems mentioned in the older article. Then, check the solution for the much harder problem in the article I linked here.

Study the two problems side-by-side. At first glance, they don’t look all that similar, but the “bones” of the two problems are quite close. A 760 scorer has the math and test-taking skills to make this kind of connection.

Wildcards
There are a couple of wildcards to take into account. First, serendipity plays a part in our performance on the GMAT, and the higher we go, the more of an impact serendipity can have. (Serendipity is a prettier word for luck.) A few additional questions in an area of strength vs. an area of weakness can make a 20 or 30 point difference in your score, especially at higher levels.

Second, the mastery described above relies heavily upon an ability to create and recall memories. Those with a greater capacity to remember and recall a large volume of information will find it easier to reach higher levels on the test. The mastery described above also relies heavily upon an ability to recognize patterns. Again, those with a greater capacity to study patterns and to recognize similar patterns in new information will also find it easier to reach higher levels on the test.

Take-aways
If you’re going to score 700+ on the GMAT, you have to develop the ability to recognize what to do on at least some of the problems that you see on the official test (problems that, by definition, you’ll never have seen before). Then, you need to get better at this skill; the single biggest difference between a 760-level tester and a 700-level tester is the ability to recognize a larger percentage of the problems you see.

How to do that? You have to learn the fundamental content and the strategies for tackling the different kinds of question types, of course. Then, you need to lift yourself to the 2nd Level of Learning on the GMAT. Follow that link to learn how to study in a way that will increase the number of problems you can recognize when you take the test.

Good luck and happy studying!
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The Distinction between a 700 and a 760 Score on the GMAT [#permalink]
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FROM Manhattan GMAT Blog: The Distinction between a 700 and a 760 Score on the GMAT

I first wrote about this topic back in 2010. I’ve seen so many people lately on the forums who are going for a 750 or 760+ that I decided to revive the conversation.

My first version of this article started out with some reservations about this topic—and those reservations haven’t gone away. In fact, they’ve grown a little. Just yesterday, I answered a forum question from someone who told me that his or her desired school required a 750 or higher.

I don’t know a single school that says it requires a 750 or higher—and if there is one, then that admissions team is using the test incorrectly and people should be skeptical about attending that school. As far as the GMAT can tell, someone scoring 720 and someone scoring 750 are both equally capable of performing well at any particular business school. (Other reasons may exist for preferring one person over the other, but the GMAT is not one of those reasons.)

Second of all, I talk to many people on the forums who set a goal score and just assume that, as long as they study hard enough, they can get that score. In fact, they think there’s something wrong with them when they struggle to get there. The GMAT is not a static school test, where everyone could theoretically score the top score if they just studied enough. By definition, only 1 percent of test-takers will score 760 or higher.

That loops us back around to my first concern: given that so few people achieve these scores, any school that required a 750 or 760 (or higher) would not have very many candidates to choose from among when building its next MBA class. In addition, the school would build a very lopsided class. The GMAT is one admissions tool, but only one. There are many very strong candidates who do not hit the top level on this particular piece of the admissions puzzle.

In short, most people going for this kind of crazy-high score would be far better off using that time to work towards a promotion at work, or volunteer, or spend more time with family and friends. That is, unless you want to teach for my company—we’re the only organization I know that actually does require a 760+.

I also have to discuss something about the ranges I’ve chosen, 700 versus 760. You receive quant and verbal sub-scores on the GMAT, which are combined into a three digit score. The sub-scores can be quite different (or pretty similar) to get a 700 (or any score).

This article will assume that the sub-scores are roughly similar (that is, the person does not have a big disparity between the two sub-scores). If such a disparity does exist—for example, a 70th percentile quant score and a 95th percentile verbal score—then that person may score a 700, but will not have mastered everything listed below for the quant portion. At the same time, that person will likely have mastered many, if not most, things listed under the “760-level” section below for the verbal portion.

Mastery
Before we can dive into what mastery means for each of these two groups, we have to define something: what it means to recognize what to do on a problem. If you recognize what to do, then when you see a new question, you quickly (within about 20 to 30 seconds) make a connection to some problem you’ve done in the past; there’s some similarity between the two problems and you recognize that similarity.

As a result of that recognition, you now know what to do in order to solve this problem, because you can use the same (or a very similar) solution method. You will also be aware of the common mistakes you might make or traps you might fall into on a question like this one. You may save a little time and you’re more likely to answer the problem correctly.

By contrast, if you don’t recognize what to do, you have to figure out what to do “from scratch” (from the beginning); that slows you down and doesn’t give you any advantage in terms of accuracy.

Okay, here are the differences in mastery for 700-level and 760-level scorers:



What jumped out at you? I’d like to point out a few important points.

First, even at the 760+ level, you won’t recognize what to do with everything. You also do have to guess, even at the highest levels.

Second, the key difference is that those capable of scoring 760+ are able to recognize what to do on large portions of the test. This does not mean that they’ve seen that exact problem (or a close one) with different words or numbers.

Rather, it means that they recognize the type of reasoning used or the type of trap set or something about the way the problem was put together. They may still have to adapt to some kind of unexpected twist—but they have a much better chance of doing so successfully in the limited available time because they recognize the underlying structure of the problem.

Read this article about Decoding the Prime Disguise for an example. Note that the beginning of the article has a link to a prior article—follow the link and read the older article first. Try the two problems mentioned in the older article. Then, check the solution for the much harder problem in the article I linked here.

Study the two problems side-by-side. At first glance, they don’t look all that similar, but the “bones” of the two problems are quite close. A 760 scorer has the math and test-taking skills to make this kind of connection.

Wildcards
There are a couple of wildcards to take into account. First, serendipity plays a part in our performance on the GMAT, and the higher we go, the more of an impact serendipity can have. (Serendipity is a prettier word for luck.) A few additional questions in an area of strength vs. an area of weakness can make a 20 or 30 point difference in your score, especially at higher levels.

Second, the mastery described above relies heavily upon an ability to create and recall memories. Those with a greater capacity to remember and recall a large volume of information will find it easier to reach higher levels on the test. The mastery described above also relies heavily upon an ability to recognize patterns. Again, those with a greater capacity to study patterns and to recognize similar patterns in new information will also find it easier to reach higher levels on the test.

Take-aways
If you’re going to score 700+ on the GMAT, you have to develop the ability to recognize what to do on at least some of the problems that you see on the official test (problems that, by definition, you’ll never have seen before). Then, you need to get better at this skill; the single biggest difference between a 760-level tester and a 700-level tester is the ability to recognize a larger percentage of the problems you see.

How to do that? You have to learn the fundamental content and the strategies for tackling the different kinds of question types, of course. Then, you need to lift yourself to the 2nd Level of Learning on the GMAT. Follow that link to learn how to study in a way that will increase the number of problems you can recognize when you take the test.

Good luck and happy studying!
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Re: Updates from Manhattan GMAT [#permalink]
I am having one doubt after going through your GMAT material for Algebra.

Chapter 3 Exponents , page number 39 says

-2^4 is not equal to (-2)^4.

This is peculiar as I have not seen this differentiation anywhere in my studies. I have had a good Maths background and am a Engineering graduate. Is this notation peculiar to GMAT only ?
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Re: Updates from Manhattan GMAT [#permalink]
Is your Maths set sufficient for GMAT ? For eg I dont see any mention of topics like probability, permutation/combination etc.

For eg the formula mentioned in the link (four-boys-picked-up-30-mangoes-in-how-many-ways-can-they-98701.html#p761146) is no where mentioned in the Manhattan material.


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When is it Time to Guess on Verbal? [#permalink]
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FROM Manhattan GMAT Blog: When is it Time to Guess on Verbal?

As dedicated readers of this blog may have guessed, this is a follow up to my earlier post When is it Time to Guess on Quant? Timing troubles are not, however, exclusive to the Quant section, so in this piece I’ll talk about some common scenarios that bedevil students on the Verbal section.
As with Quant, not all guesses are created equal. The earlier you decide to guess, the more likely that you will make a random guess. If, on the other hand, you’re far enough into the question that you’ve eliminated 2-3 answer choices, then you’ll be making an educated guess.

One immediate difference between guessing on Quant and Verbal is that guessing strategy is essentially identical for both Problem Solving and Data Sufficiency questions. Each of the Verbal question types, on the other hand, has less in common. That being said, there are a lot of parallels in guessing strategy among the three types.

No matter the question, there are really three distinct stages at which it becomes a better idea to guess than to keep going. I’ll briefly describe each stage, then show how it connects to each of the Verbal question types.

Stage 1: No Clear Starting Point

As a general rule, if you haven’t really made progress on a question after 30 seconds or so, it’s usually a good idea to just make a random guess and save your energy for a question you’re more comfortable with.

Reading Comprehension Stage 1: I don’t know where in the passage to look.

The great thing about Reading Comprehension (or at least its saving grace) is that the correct answer has to have support in the passage. With the vast majority of RC questions, as long as you can find and reread the relevant portion of the passage, you can find an answer choice that will match what you read. In fact, you should be able to answer to come up with your own answer to most RC questions before you even look at the answer choices.

Many questions provide good clues as to where in the passage to look for the answer (seriously – a surprising amount of questions are very helpful in that regard). Things get much tougher when they don’t. So here’s your first big clue that it may be time to guess. If you’ve read the question, and you’ve skimmed through the passage looking for an answer, and you still don’t feel like you found what the question was asking about, it’s time to guess.

At this point, you could guess randomly, but I would recommend taking one quick pass through the answer choices. If any choice contradicts your understanding of the passage, eliminate it. After you’ve each answer once, pick from the remaining.

Sentence Correction Stage 1: I don’t understand the sentence and the underline is long.

On the Verbal section, you have to answer 41 questions in 75 minutes, which is less than 2 minutes per question. Critical Reasoning and Reading Comprehension are naturally time-consuming, so that time is going to have be saved largely on Sentence Correction. Remember that you only have an average of 1 minute and 20 seconds to answer these things.

If you’re struggling to even understand what the sentence is saying, then it will almost certainly take too long to properly analyze the answer choices, especially if the underline is long. No need to fight through the pain. Just take a quick scan through the answer choices and pick one that doesn’t sound immediately wrong.

Critical Reasoning Stage 1: I don’t understand what the argument is saying.

To my mind, good process on Critical Reasoning questions means being in control the whole way through the process. The worst situation to be in is one in which you’re hoping that the answer choices will help you make sense of the argument. Four out of the five answer choices are actively trying to trick you, and the GMAT has gotten pretty good at tricking people over the years. By the time you get to the answer choices, you need to understand the argument well enough to effectively evaluate each choice.

Consequently, if you’ve read the argument two or three times, and still can’t articulate to yourself the link between the premises and the conclusion, you shouldn’t waste time with the answer choices.

 

Stage 2: Early Signs of Trouble

The last stage described problems that seemed difficult right from the start. Even if a question doesn’t seem difficult, though, you still need to make progress. When you first look through the answer choices, you may not identify the right answer right away, but you should be able to eliminate two or three wrong answers. If you can’t, it will probably take too long to get all the way to the right answer. Either guess randomly or read through the answers once more and pick the one that sounds the best.

Reading Comprehension Stage 2: None of the answers match what I read.

So at this point, you’ve read the question, you’ve found the relevant part of the passage, and you’re ready to find a match in the answer choices. The problem is, none of them seem to match what you read. Not only that, but you don’t feel that any of the choices contradict the passage, so you can’t really eliminate them either. Chances are that you’ve either read the wrong part of the passage, or you read the right part, but didn’t read enough.

At this point, you would need to go back to the passage and keep reading. If you haven’t spent much time on the question, then go for it. But if you’ve already spent 45 seconds or more, it’s probably better to just pick an answer and move on.

Sentence Correction Stage 2: I understand the sentence, but I can’t find anything wrong in the answer choices.

So you’ve read the sentence and it makes sense, and there’s nothing obviously wrong with it. Next step is to look for differences in the answer choices. So you read through the answer choices, and you see differences, but you’re not really sure which version is better. By the time you’ve read through choice (E), you haven’t eliminated any, or you’ve only gotten rid of one.

This is tough, because it probably feels like you should be able to work through this one. And maybe with enough time you could. But if you’ve spent this much time looking through it and nothing has really clicked, it’s hard to know how much more time you’ll need. At this point, either guess randomly or read through the remaining choices once more and pick the one that sounds the best.

Critical Reasoning Stage 2: I understood the argument, but none of these choices seem obviously right or wrong.

You’ve read the argument, it makes sense, and you’re ready to evaluate the answer choices. Then you read through them and eliminate either none of them or all of them. Either way, it means something’s wrong.

Once again, it probably feels like you should be able to get this one. And once again, the problem is that you don’t know how long that will take. Better to get out now before you end up spending 4 minutes on it. As usual, either guess randomly or take one last look through the choices and pick the one you feel best about.

 

Stage 3: The Home Stretch

This last stage is all about one thing: what to do when you get it down to those two final answers. Hopefully, one of them is the right answer, but either way, you’re going to have to choose. The danger when you get down to the final two is refusing to make a decision. If you’ve gotten this far, and assuming you haven’t already used up extra time, then you definitely want to spend some extra time comparing the choices. But if you’ve read each of them 3+ times, and you’re still not sure, don’t let this question drag on.

Reading Comprehension Stage 3: Down to the last two.

In my experience, when choosing between the last two answers on a Reading Comp question, it’s more about proving an answer wrong than proving an answer right. If both sound good, then you have to read each one carefully and make sure every word matches up with the passage. If even one word is off, eliminate that choice.

After you’ve read through each one several times though, it’s time to make a decision. Even if you’re not 100% sure, pick the choice that you feel better answers the question.

Sentence Correction Stage 3: Down to the last two.

You’ve read each choice, and you’ve spotted all the ways in which they differ. But they both sound fine! There aren’t any easy answers on this one. Look at each difference one more time and make sure to read the full sentence again, but be prepared to move on if you’re still not sure.

I’ve seen a lot of people spend three and a half minutes on a Sentence Correction, of which a full two minutes was spent on the last two. In most cases, I’d rather that person get the question wrong in two minutes than right in three and a half.

Critical Reasoning Stage 3: Down to the last two.

I don’t know about you, but I often find that by the time I’ve gotten a CR down to two choices I either don’t remember exactly what I’m looking for or I’ve forgotten some details from the argument. Either way, I’ve lost the ability to make a good decision.  On almost every CR question I do, I find myself going back and rereading the argument and the question at some point in the problem.

If you’re down to two and can’t choose, go back and reread the argument and the question to refocus you on the task at hand. Then read the last two choices one more time. If one jumps out at you, great! But if not, you still have to pull the trigger. You’ve done what you could, now save some time and energy for the next questions.

Wrap Up

This post has been not only about guessing strategy, but also about the steps you can take when you run into trouble. Guessing isn’t always about running away at the first sign of trouble. For every question type, there are things you can do to try to get yourself back on track. But all of these scenarios have one thing in common: no matter how far along you are in a problem, once you hit a wall you need to make your best guess and move on.

 [d1]Include link to blog post: https://www.manhattangmat.com/blog/inde ... -on-quant/
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Can you Spot the Meaning Error? [#permalink]
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FROM Manhattan GMAT Blog: Can you Spot the Meaning Error?

Sentence Correction tests grammar, yes, but it also tests meaning. In fact, a decent chunk of grammar actually revolves around meaning in the first place.

Try this GMATPrep® problem from the free exams and then we’ll talk about it.

* “In the mid-1920s the Hawthorne Works of the Western Electric Company was the scene of an intensive series of experiments that would investigate changes in working conditions as to their effects on workers’ performance.

“(A) that would investigate changes in working conditions as to their effects on workers’ performance

“(B) investigating the effects that changes in working conditions would have on workers’ performance

“(C) for investigating what the effects on workers’ performance are that changes in working conditions would cause

“(D) that investigated changes in working conditions’ effects on workers’ performance

“(E) to investigate what the effects changes in working conditions would have on workers’ performance”

What did you think? I did give away that this problem tests meaning; did you spot any meaning issues?

The first step on SC is to glance at the start of the underline (even before you read the sentence). The underline starts halfway through on the word that. The word that can signal issues with modifiers or with the underlying sentence structure, so keep these possibilities in mind as you move to the next step, reading the sentence.

Did you like the original sentence or did you think there was something wrong with it?

In fact, the original has a meaning issue! We have a starting point. The sentence talks about something that happened nearly 100 years ago, so it doesn’t make sense to say that these experiments would investigate something. The place was the scene of the experiments conducted at that time in the past.

You can use would properly in certain past conditions: She would have eaten the fish if she hadn’t been allergic. If she ate fish, she would have an allergic reaction. The test results showed that feeding her fish would cause an allergic reaction.

You can’t, then, just cross off any other answers that also contain would; you’ll have to read to figure out the meaning.

Answers (B), (D), and (E) all use would, but they don’t say would investigate. Instead, all three talk about what effects changes in working conditions would cause or would have.

This usage is acceptable because the information is conveying a cause-effect relationship: changes cause effects. By definition, the effects have to happen later than the changes. The word would can be used to indicate a “future in the past” meaning, similar to the example The test results showed that feeding her fish would cause an allergic reaction.

Hmm, that starting point allowed the elimination of only one answer, (A). Back to the drawing board. What next?

If you noticed anything else about the original sentence that you didn’t like, try that next. Otherwise, scan the answers vertically to spot differences and tackle one of those differences. Let’s follow the latter path next.

The opening of each answer is as follows:

The Hawthorne Works was the scene of a series of experiments…

(A) that would investigate…

(B) investigating…

(C) for investigating…

(D) that investigated…

(E) to investigate…

Idiom time. It’s acceptable to say a series of experiments that did something or a series of experiments investigating something.

It isn’t acceptable to say a series of experiments for investigating something. If you wanted to convey that kind of meaning, you’d need to say something similar to a series of experiments designed to investigate something. You can also drop the word designed and go straight into to investigate.

Okay, (A) and (C) down, three to go. What next?

Here’s where it gets a bit messy. The remaining portions of the choices differ enough that you can’t compare a single word or a couple of words. Now you have to look at an entire chunk of each sentence.

Here are (B), (D), and (E) again. What are these things trying to say?

“(B) investigating the effects that changes in working conditions would have on workers’ performance

“(D) that investigated changes in working conditions’ effects on workers’ performance

“(E) to investigate what the effects changes in working conditions would have on workers’ performance”

Something like: when there were changes in working conditions, what effects would there be on performance?

Do all three options convey this logically and unambiguously?

As it turns out, no. Take a look at answer (D). Strip out the modifiers:

“(D) that investigated changes in working conditions’ effects on workers’ performance”

(D) that investigated changes in effects on performance

This choice doesn’t talk about changes in the conditions. It talks about changes in the effects. It doesn’t make any sense to jump straight to the effects—you change the input (conditions) to see how the output then changes. Very tricky!

Answers (B) and (E) are very close. The only differences are towards the beginning.

“(B) investigating the effects that changes in working conditions would have on workers’ performance

“(E) to investigate what the effects changes in working conditions would have on workers’ performance”

This last one is the trickiest of all. Consider these two examples:

New York was the scene of a study investigating the theft.

New York was the scene of a study to investigate what the theft.

You probably knew immediately that the second sentence is wrong. Why? Once you toss in the word what, you need a clause (a verb) to go with theft: New York was the scene of a study to investigate what the theft then led to in future.

Choice (E) uses the word what, but this choice doesn’t make the effects portion a clause. The verb would have applies to changes. You could say something like “to investigate what the effects on workers’ performance are when there are changes in working conditions.” That sentence is a little clunky, but it does contain the necessary verb. (Notice that answer (C) also uses the word what and that one does talk about what the effects are.)

That takes us down to one answer, (B). This answer uses an acceptable idiom (a series of experiments investigating…) and conveys the appropriate meaning (they were investigating the effects that resulted from changes in working conditions).

In my opinion, the test writers purposely used would investigate incorrectly in (A) hoping that people would then automatically eliminate other answers because they also use what seems to be a similar, incorrect verb structure. Conveniently, the correct answer contains would have, so anyone doing this will have just crossed off the correct answer. That leaves answer (D), which seems just fine if you don’t notice that the meaning is illogical (and that choice is written confusingly enough that it would be easy to overlook the meaning issue).

The correct answer is (B).

Key Takeaways: Meaning in SC
(1) Always go for the low-hanging fruit first: anything that you know how to tackle easily and confidently. This will help you to narrow down the answers before you have to get to the toughest stuff, making it easier (though not easy!) for you to try to strip out the trickiest traps.

(2) When answers change as much as the ones in this example do, you are probably looking at a Structure, Modifier, Meaning, or Parallelism issue (or multiple issues intertwined). You’ll likely have to compare entire chunks of the answers, not just a few words at a time.

(3) When you do have to compare chunks, first get the meaning straight in your head: what is the sentence actually trying to convey? Be on the lookout for choices that twist the meaning in an illogical or ambiguous way; you can cross these off.

* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.

 
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GMAT INTERACT: Coming Soon! [#permalink]
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FROM Manhattan GMAT Blog: GMAT INTERACT: Coming Soon!


Available June 16th, GMAT INTERACT will forever change the way you think about test prep. We took the best of our GMAT curriculum, gathered the world’s greatest instructors, and reimagined all of the possibilities. Welcome to GMAT INTERACT.

What is GMAT INTERACT?

GMAT Interact is a comprehensive self-study program unlike anything you’ve tried before. It features 30+ interactive lessons that are funny, intuitive, and directed by you.

Never watch another boring test prep video again!

You’ve seen them. You’ve might taken notes from them. Heck, you might have even fallen asleep to a few of them. True to its name, GMAT Interact is different from typical online courses and static video lessons. It’s an elegant integration of instruction and interactive technology. Every lesson is taught by an expert Manhattan Prep instructor and includes dozens of individual branching points. If you get something right, we may take you to a tougher problem. If you get something wrong, we may take you through a detailed lesson. No two people will see the same thing.

Gasp! It isn’t boring!

Let’s face it – GMAT content isn’t that riveting. It’s grammar rules and algebraic equations, it’s long division and obscure vocab. But your prep doesn’t have to be boring! GMAT Interact was designed to engage your whole brain – every lesson is fresh, funny, and driven by the choices you make.

Prep Made Personal

GMAT Interact was designed around the student-teacher connection. An instructor guides you through each lesson, asking you questions and prompting you to think about the content presented. Every response you give changes the lesson you see.

Anytime, Anywhere

This program is entirely self-paced. You can stop, start, or go back anytime you want. Every lesson is delivered in crisp HD and is available on your computer or mobile device. Prep where you are, when you want.

Curious? Try Interact Now

The complete GMAT INTERACT program (coming in June 16th!) will teach every section of the GMAT, but you can get started on the Integrated Reasoning section right now, for free. It won’t be available for free forever, though, so be sure to check it out before it’s gone!
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Can you Spot the Meaning Error? (part 2) [#permalink]
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FROM Manhattan GMAT Blog: Can you Spot the Meaning Error? (part 2)
Last time, we tried a problem that tested meaning; we also discussed how to compare entire chunks of the answer choices. Today, we’re going to combine those two things into a new skill.

Try this GMATPrep® problem from the free exams and then we’ll talk about it.

* “The striking differences between the semantic organization of Native American languages and that of European languages, in both grammar and vocabulary, have led scholars to think about the degree to which differences in language may be correlated with nonlinguistic differences.

“(A) that of European languages, in both grammar and vocabulary, have

“(B) that of European languages, including grammar and vocabulary, has

“(C) those of European languages, which include grammar and vocabulary, have

“(D) those of European languages, in grammar as well as vocabulary, has

“(E) those of European languages, both in grammar and vocabulary, has”

At first glance, the underline isn’t super long on this one, Glance down the first word of each answer. What does a split between that and those signify?

Both are pronouns, so they’re referring to something else in the sentence. In addition, one is singular and one is plural, so it will be important to find the antecedent (the word to which the pronoun refers).

Next, read the original sentence. What do you think? It isn’t super long but it still manages to pack in some complexity. Learn how to strip it down and you’ll be prepared for even more complex sentence structures.

My first thought was: okay, now I see why they offered that vs. those. Should the pronoun refer to the plural differences or to the singular organization?

It could be easy to get turned around here, so strip down the sentence structure:

The differences between X and __________.

What should come next? Y! The sentence is making a comparison and that comparison is incomplete until it finishes off with the second item. Since Y needs to be parallel to X, the pronoun should match organization: that.

The word of is another clue. Here’s the full structure of the comparison:

between the organization of A and (the organization) of B.

Organization of can be replaced with that of, and you do need to repeat the word of. If you don’t, the sentence would effectively read:

between the organization of A and the organization B.

You can’t say the organization B (unless B is the name of the organization); it has to be the organization of B.

Excellent. Eliminate answers (C), (D), and (E).

(As an aside, if you have ever heard the myth that, if you need to guess, you should choose the more common difference…take a look at this problem. The more common difference, those, leads to the wrong answer. In this case, the test writers must have data that people are very likely to make this mistake—it doesn’t sound bad to me, either, though I know it’s wrong!)

What next? If you still had 3 or 4 choices left, I’d probably recommend examining the original sentence for other errors. Because there are only 2 choices left, I recommend comparing the two and dealing with whatever differences you see.

“(A) that of European languages, in both grammar and vocabulary, have

“(B) that of European languages, including grammar and vocabulary, has

There are two differences: in both vs. including and have vs. has. Deal with whichever you think will be easier for you. I think most people will find the second one more approachable, so let’s tackle that one.

Again, the difference lies in number: singular vs. plural. What is the subject for this verb?

Go back to your prior examination of the sentence structure:

The differences between X and Y, (in both/including) G and V, (have/has)…

Ah, okay! They have nested a bunch of modifiers in between the subject and verb, hoping that we’ll pick up the wrong subject. Check this out:

The differences [between X and Y], [modifier], have/has…

The core of the sentence is The differences have led scholars to think (about something). The sentence needs the plural verb have. Answer (B) is wrong.

The correct answer is (A).

What about that in both / including / etc. difference?

Answers (A) through (D) are arguably all okay in this area. I don’t love (B)—it isn’t the way a native speaker would typically speak—but the test isn’t trying to distinguish between native and non-native speakers, so the subject-verb agreement error is included as the definitive error.

Answer (E) breaks parallelism. It should say either in both grammar and vocabulary or both in grammar and in vocabulary.

Join us next time for another look at these topics!

Key Takeaways: Strip to the Core
(1) In the end, this problem really tested number agreement (via both a pronoun and a verb), which seems like it should be easy. Notice how hard they can make things, though, when they nest a bunch of modifiers together between the subject and the verb. If you learn how to read or group chunks of words, you can strip out the modifiers to get to the core of the sentence.

(2) When you do want to strip the sentence down, examine the core first: subjects and verbs. Eliminate any errors, then see what you have left. At that point, if you have only 2 or 3 answers left, it’s best to compare those answers for differences.

(3) Don’t automatically deal with the first difference that you see. Ask yourself whether you actually know what to do with it. Sometimes, there’s a more clear difference later on, as in this problem. Have vs. has is easier to handle than that whole in both / including / which / etc issue.

* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.
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Sneak Peek: a behind-the-scenes look at GMAT INTERACT [#permalink]
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FROM Manhattan GMAT Blog: Sneak Peek: a behind-the-scenes look at GMAT INTERACT
With GMAT INTERACT™ coming June 16th, we’d like to take you behind-the-scenes to explore some fun facts about GMAT INTERACT and the creation process that has made all of this possible. Here are a few fun facts we’d like to share.

1. GMAT INTERACT was years in the making.



 

It took over 6,000 hours of development to bring GMAT INTERACT to life. An expert team of Manhattan Prep designers, coders, developers, and instructors worked for over three years on the design and development of the platform to create a user experience that is unlike anything else in test prep.

2. This is the first GMAT learning platform that is truly interactive.



GMAT INTERACT is a comprehensive on demand, self-paced program that features 35+ lessons that are interactive, funny, and completely directed by you. No two people see the same thing. Designed around the student-teacher connection, an expert Manhattan Prep instructor will guide you through each section of the GMAT, asking you questions and prompting you to think about the content presented. What’s more: every response you give tailors the lesson you’ll receive.

3. We’ve made GMAT Fun!



Manhattan GMAT is known for our incredible instructors (just check out our Beat The GMAT Verified Reviews). Not only are our teachers top scoring GMAT experts, they’re also fun and engaging—and we’ve put them front and center in GMAT INTERACT. And, we may have also thrown in a sock puppet or two…

To give you a taste of the fun you can expect, here are some facts about GMAT INTERACT:

o Number of times you get to see an Tommy dance: 3

o Number of times Whitney Garner laughs on camera: uncountable

o Most takes we needed for a clip: 16

o Number of times we cursed on camera and had to toss the clip: 11

o Number of dolphin drawings used: 1

o Number of dinosaur cat robots destroyed in production: 1

o Number of bubbles used in the Evil Grammar Lab: 521

o Number of caveman used in production: 1

4. With GMAT INTERACT, you don’t get 1 Manhattan Prep instructor – you get 11!



When we say that GMAT INTERACT is comprehensive – we mean it! We put eleven of our most accomplished instructors in front of the camera, take-after-take, and are delivering them to your computer and mobile devices wherever you are. Not just a video, our instructors will engage with you based on the responses and answers you input.

5. You don’t have to wait until June 16th to try GMAT INTERACT!



While the full version of GMAT INTERACT won’t be available until June 16th for purchase, you can try GMAT INTERACT for Integrated Reasoning right now, for free. So what are you waiting for? Jump in and have some fun! Test prep doesn’t have to be boring ever again!
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Sneak Peek: a Behind-the-Scenes Look at GMAT INTERACT [#permalink]
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FROM Manhattan GMAT Blog: Sneak Peek: a Behind-the-Scenes Look at GMAT INTERACT
With GMAT INTERACT™ coming June 16th, we’d like to take you behind-the-scenes to explore some fun facts about GMAT INTERACT and the creation process that has made all of this possible. Here are a few fun facts we’d like to share.

1. GMAT INTERACT was years in the making.



 

It took over 6,000 hours of development to bring GMAT INTERACT to life. An expert team of Manhattan Prep designers, coders, developers, and instructors worked for over three years on the design and development of the platform to create a user experience that is unlike anything else in test prep.

2. This is the first GMAT learning platform that is truly interactive.



GMAT INTERACT is a comprehensive on demand, self-paced program that features 35+ lessons that are interactive, funny, and completely directed by you. No two people see the same thing. Designed around the student-teacher connection, an expert Manhattan Prep instructor will guide you through each section of the GMAT, asking you questions and prompting you to think about the content presented. What’s more: every response you give tailors the lesson you’ll receive.

3. We’ve made GMAT Fun!



Manhattan GMAT is known for our incredible instructors (just check out our Beat The GMAT Verified Reviews). Not only are our teachers top scoring GMAT experts, they’re also fun and engaging—and we’ve put them front and center in GMAT INTERACT. And, we may have also thrown in a sock puppet or two…

To give you a taste of the fun you can expect, here are some facts about GMAT INTERACT:

o Number of times you get to see an Tommy dance: 3

o Number of times Whitney Garner laughs on camera: uncountable

o Most takes we needed for a clip: 16

o Number of times we cursed on camera and had to toss the clip: 11

o Number of dolphin drawings used: 1

o Number of dinosaur cat robots destroyed in production: 1

o Number of bubbles used in the Evil Grammar Lab: 521

o Number of caveman used in production: 1

4. With GMAT INTERACT, you don’t get 1 Manhattan Prep instructor – you get 11!



When we say that GMAT INTERACT is comprehensive – we mean it! We put eleven of our most accomplished instructors in front of the camera, take-after-take, and are delivering them to your computer and mobile devices wherever you are. Not just a video, our instructors will engage with you based on the responses and answers you input.

5. You don’t have to wait until June 16th to try GMAT INTERACT!



While the full version of GMAT INTERACT won’t be available until June 16th for purchase, you can try GMAT INTERACT for Integrated Reasoning right now, for free. So what are you waiting for? Jump in and have some fun! Test prep doesn’t have to be boring ever again!
This Blog post was imported into the forum automatically. We hope you found it helpful. Please use the Kudos button if you did, or please PM/DM me if you found it disruptive and I will take care of it. -BB
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Can you Spot the Meaning Error? (part 3) [#permalink]
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FROM Manhattan GMAT Blog: Can you Spot the Meaning Error? (part 3)

Welcome to the final installment in a series of three articles about meaning and sentence structure in sentence correction. Our first one tested meaning and also covered issues related to having to break the sentence into chunks. In the second, we talked about how to use that chunk idea to strip the sentence down to the core structure vs. the modifiers.

Today, I’ve got a third GMATPrep® problem for you following some of these same themes (I’m not going to tell you which ones till after you’ve tried the problem!).

* “Today’s technology allows manufacturers to make small cars more fuel-efficient now than at any time in their production history.

“(A) small cars more fuel-efficient now than at any time in their

“(B) small cars that are more fuel-efficient than they were at any time in their

“(C) small cars that are more fuel-efficient than those at any other time in

“(D) more fuel-efficient small cars than those at any other time in their

“(E) more fuel-efficient small cars now than at any time in”

The first glance doesn’t indicate a lot this time. The answers change from small cars to more (fuel-efficient small cars), which isn’t much of a clue. Go ahead and read the original sentence.

What did you think? When I first read it, I shrugged and thought, “That sounds okay.” If you can’t come up with something to tackle from the first glance or the first read-through, then compare answers (A) and (B), looking for differences.

Hmm. I see—do we need to say that are more fuel-efficient? Maybe. Answer (C) uses that same structure. Oh, hey, answer (C) tosses in the word other! I know what they’re doing!

If you’ve seen the word other tested within a comparison before, you may know, too. If not, get ready to make a note. Take a look at these two sentences:

Auna is taller than any woman in her class.

Auna is taller than any other woman in her class.

What’s the difference? Are both acceptable or only one?

When you’re making a comparison in which one part of the comparison falls into the same group as the rest, you have to find a way to distinguish that one part.

In this case, Auna is a part of the class. It’s impossible, then, for her to be taller than any woman in her class, because she herself is one of those women! She has to be taller than any other woman in her class, not including herself.

By the same token, today’s small cars can’t be more fuel-efficient than at any time in their history, because that history includes right now. They have to be more fuel-efficient now than at any other time.

Answers (A), (B) and (E) are all wrong for this reason, but this meaning error isn’t necessarily immediately apparent just from reading the original sentence. The definitive clue is the addition of the word other in answers (C) and (D).

Now that you’re down to two, compare them:

“(C) small cars that are more fuel-efficient than those at any other time in

“(D) more fuel-efficient small cars than those at any other time in their”

Now, be incredibly careful. There are two differences: small cars that are move fuel-efficient vs. more fuel-efficient small cars and in vs. in their.

Some people will use concision at this point. Be very wary about using concision. First of all, although answer (D) is a little more concise at the beginning, answer (C) is more concise at the end, so how can you decide based on concision?

Second of all, concision is usually a mask for some other issue, typically meaning or modifiers. Dig deeper. Take a look at the full sentence; here is it with (C) inserted into the underline.

“Today’s technology allows manufacturers to make small cars that are more fuel-efficient than those at any other time in production history.”

And (D):

“Today’s technology allows manufacturers to make more fuel-efficient small cars than those at any other time in their production history.”

When modifiers move around, check the meaning.

The first answer says that today’s small cars are more fuel-efficient.

The second answer says that… the cars are more fuel-efficient? Or that there are more of these types of cars? I’m not actually sure.

Hmm. Ambiguity is bad.

Also, whose production history are we talking about? Answer (C) just says in production history, but (D) tosses in the pronoun their. Does their refer to cars? The manufacturers? This choice is unclear; eliminate it.

The correct answer is (C).

Key Takeaways: Examine Meaning when Modifiers Move
(1) Only some of the answers included the modifier other. When a modifier appears or disappears, think about the meaning of the sentence. In particular, when you see the word other included in a comparison, examine that comparison. If the X portion is itself a part of the Y group, then you need to add the word other to make clear that X is not being compared to itself. This car is faster than any other car.

(2) When modifiers move around in a sentence, think about meaning. The placement of modifiers absolutely affects what is being modified, so moving something around may cause the sentence to be illogical or ambiguous.

(3) Ambiguity can be difficult to spot when you already know the intended meaning of the sentence; since you already know what the sentence is trying to say, you’re likely to read right over the ambiguity. Actively look for ambiguity (or lack of logic) when you see modifiers moving around.

* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.

Read Can you Spot the Meaning Error? (part 1) and Can You Spot the Meaning Error? (Part 2).
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Memorize this and pick up 2 or 3 GMAT quant questions on the [#permalink]
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FROM Manhattan GMAT Blog: Memorize this and pick up 2 or 3 GMAT quant questions on the test!

Memorize what? I’m not going to tell you yet. Try this problem from the GMATPrep® free practice tests first and see whether you can spot the most efficient solution.



All right, have you got an answer? How satisfied are you with your solution? If you did get an answer but you don’t feel as though you found an elegant solution, take some time to review the problem yourself before you keep reading.

Step 1: Glance Read Jot

Take a quick glance; what have you got? PS. A given equation, xy = 1. A seriously ugly-looking equation. Some fairly “nice” numbers in the answers. Hmm, maybe you should work backwards from the answers?

Jot the given info on the scrap paper.

Step 2: Reflect Organize

Oh, wait. Working backwards isn’t going to work—the answers don’t stand for just a simple variable.

Okay, what’s plan B? Does anything else jump out from the question stem?

Hey, those ugly exponents…there is one way in which they’re kind of nice. They’re both one of the three common special products. In general, when you see a special product, try rewriting the problem usually the other form of the special product.

Step 3: Work

Here’s the original expression again:



Let’s see.



Interesting. I like that for two reasons. First of all, a couple of those terms incorporate xy and the question stem told me that xy = 1, so maybe I’m heading in the right direction. Here’s what I’ve got now:



And that takes me to the second reason I like this: the two sets of exponents look awfully similar now, and they gave me a fraction to start. In general, we’re supposed to try to simplify fractions, and we do that by dividing stuff out.



How else can I write this to try to divide the similar stuff out? Wait, I’ve got it:

The numerator: 

The denominator: 

They’re almost identical! Both of the 
terms cancel out, as do the 
terms, leaving me with:



I like that a lot better than the crazy thing they started me with. Okay, how do I deal with this last step?

First, be really careful. Fractions + negative exponents = messy. In order to get rid of the negative exponent, take the reciprocal of the base:



Next, dividing by 1/2 is the same as multiplying by 2:



That multiplies to 16, so the correct answer is (D).

Key Takeaways: Special Products

(1) Your math skills have to be solid. If you don’t know how to manipulate exponents or how to simplify fractions, you’re going to get this problem wrong. If you struggle to remember any of the rules, start building and drilling flash cards. If you know the rules but make careless mistakes as you work, start writing down every step and pausing to think about where you’re going before you go there. Don’t just run through everything without thinking!

(2) You need to memorize the special products and you also need to know when and how to use them. The test writers LOVE to use special products to create a seemingly impossible question with a very elegant solution. Whenever you spot any form of a special product, write the problem down using both the original form and the other form. If you’re not sure which one will lead to the answer, try the other form first, the one they didn’t give you; this is more likely to lead to the correct answer (though not always).

(3) You may not see your way to the end after just the first step. That’s okay. Look for clues that indicate that you may be on the right track, such as xy being part of the other form. If you take a few steps and come up with something totally crazy or ridiculously hard, go back to the beginning and try the other path. Often, though, you’ll find the problem simplifying itself as you get several steps in.

* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.

 

 
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