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Making no progress on PS questions [#permalink]
01 Oct 2013, 18:41

Can someone help me figure out why I can't translate the formulas I'm learning here to other problems (for PS problems). I get about 95% of 600 level+ PS problems incorrect, but when I look at the solutions, they make perfect sense to me. Earlier someone linked me to a guide they made for when to use certain formula, and I get the examples he gives, but if you wait 10 minutes, and give me an identical problem, just with the numbers in the question changed, I can't do it. I don't understand why. I used to tutor people in calculus, advanced algebras, etc. But the GMAT questions are so far beyond anything I used there. I was hoping that I would be able to memorize the formulas for the GMAT questions as easily as I did calc/algebra/etc., but honestly I'm lost. I've been studying for weeks, and my score on the PS problems is still the same. So clearly I'm doing something wrong. I need help here, I want to get in the 730-760 range, and I think I'm pretty close, but if I'm getting about 19 out of every 20 PS problems incorrect (and honestly the ones I do get right I'm guessing) that's going to hurt.

Re: Making no progress on PS questions [#permalink]
02 Oct 2013, 20:11

2

This post received KUDOS

Expert's post

AccipiterQ wrote:

Can someone help me figure out why I can't translate the formulas I'm learning here to other problems (for PS problems). I get about 95% of 600 level+ PS problems incorrect, but when I look at the solutions, they make perfect sense to me. Earlier someone linked me to a guide they made for when to use certain formula, and I get the examples he gives, but if you wait 10 minutes, and give me an identical problem, just with the numbers in the question changed, I can't do it. I don't understand why. I used to tutor people in calculus, advanced algebras, etc. But the GMAT questions are so far beyond anything I used there. I was hoping that I would be able to memorize the formulas for the GMAT questions as easily as I did calc/algebra/etc., but honestly I'm lost. I've been studying for weeks, and my score on the PS problems is still the same. So clearly I'm doing something wrong. I need help here, I want to get in the 730-760 range, and I think I'm pretty close, but if I'm getting about 19 out of every 20 PS problems incorrect (and honestly the ones I do get right I'm guessing) that's going to hurt.

Dear AccipiterQ, I'm happy to help.

Here's what I think. If your approach to math was always to memorize formulas, then even though you were doing calculus, you weren't really doing mathematics, because nothing in pure mathematics depends on memorization. There is a HUGE difference between (a) remembering something because you remember the logic of the argument, and (b) memorizing. See this blog for more of an explanation: http://magoosh.com/gmat/2012/gmat-math- ... emorizing/ To me, the sad thing is --- many folks approach GMAT math as if it's a memorization festival, and they try to memorize their way through GMAT math. Of course, the GMAT eats these people for lunch. If your understanding of math hinges on memorization, the GMAT will throw you question after question at you that will frustrate the bejeebers out of you. The test writers excel at asking questions that are enough out-of-the-box that they absolutely frustrate anyone who simply relies on memorization. In my mind, a guide of when to use what formula is symptomatic of the larger problem --- it is most certainly not something that will get you out of the larger problem of this approach. You don't need a new and improved crutch --- you need an entirely new paradigm in the way you approach math. Here's a blog in which I discuss mathematical thinking. http://magoosh.com/gmat/2013/mathematic ... -the-gmat/ First of all, for any formula you know --- consider it 100% illegal to use that formula unless you can explain, from scratch, why that formula is true. That is the level of understanding you need to have. More importantly, don't start a problem thinking "what formula should I use?" People don't get: that is a guaranteed way to fail GMAT math! Start by looking the logic of the situation --- what would happen if this number got bigger or smaller? What would happen if this were twice that? etc. Start to play with the numbers, play with the logic of the situation. Ideally, that kind of logical analysis should take you to a solution without using a formula at all. On the 37 Quant problems on the GMAT, if you use a formula to solve a problem more times than you can count on one hand, you are problem leaning on formulas too much. Finally, I get the feeling that your whole approach is very left-brain --- you like to have a list, have a recipe, have a clear set of steps to follow. If someone provides the clear set of steps, you can reliably follow them. BUT, perhaps when you have to discern a new pattern for yourself --- perhaps that's where you struggle. See this post: http://magoosh.com/gmat/2013/how-to-do- ... th-faster/ Finally, this last post is mostly for folks just starting out, but you may find a few helpful tips in here that you haven't seen elsewhere: http://magoosh.com/gmat/2013/how-to-stu ... gmat-math/

Let me know if you have any further questions. Mike _________________

Re: Making no progress on PS questions [#permalink]
03 Oct 2013, 18:40

mikemcgarry wrote:

AccipiterQ wrote:

Can someone help me figure out why I can't translate the formulas I'm learning here to other problems (for PS problems). I get about 95% of 600 level+ PS problems incorrect, but when I look at the solutions, they make perfect sense to me. Earlier someone linked me to a guide they made for when to use certain formula, and I get the examples he gives, but if you wait 10 minutes, and give me an identical problem, just with the numbers in the question changed, I can't do it. I don't understand why. I used to tutor people in calculus, advanced algebras, etc. But the GMAT questions are so far beyond anything I used there. I was hoping that I would be able to memorize the formulas for the GMAT questions as easily as I did calc/algebra/etc., but honestly I'm lost. I've been studying for weeks, and my score on the PS problems is still the same. So clearly I'm doing something wrong. I need help here, I want to get in the 730-760 range, and I think I'm pretty close, but if I'm getting about 19 out of every 20 PS problems incorrect (and honestly the ones I do get right I'm guessing) that's going to hurt.

Dear AccipiterQ, I'm happy to help.

Here's what I think. If your approach to math was always to memorize formulas, then even though you were doing calculus, you weren't really doing mathematics, because nothing in pure mathematics depends on memorization. There is a HUGE difference between (a) remembering something because you remember the logic of the argument, and (b) memorizing. See this blog for more of an explanation: http://magoosh.com/gmat/2012/gmat-math- ... emorizing/ To me, the sad thing is --- many folks approach GMAT math as if it's a memorization festival, and they try to memorize their way through GMAT math. Of course, the GMAT eats these people for lunch. If your understanding of math hinges on memorization, the GMAT will throw you question after question at you that will frustrate the bejeebers out of you. The test writers excel at asking questions that are enough out-of-the-box that they absolutely frustrate anyone who simply relies on memorization. In my mind, a guide of when to use what formula is symptomatic of the larger problem --- it is most certainly not something that will get you out of the larger problem of this approach. You don't need a new and improved crutch --- you need an entirely new paradigm in the way you approach math. Here's a blog in which I discuss mathematical thinking. http://magoosh.com/gmat/2013/mathematic ... -the-gmat/ First of all, for any formula you know --- consider it 100% illegal to use that formula unless you can explain, from scratch, why that formula is true. That is the level of understanding you need to have. More importantly, don't start a problem thinking "what formula should I use?" People don't get: that is a guaranteed way to fail GMAT math! Start by looking the logic of the situation --- what would happen if this number got bigger or smaller? What would happen if this were twice that? etc. Start to play with the numbers, play with the logic of the situation. Ideally, that kind of logical analysis should take you to a solution without using a formula at all. On the 37 Quant problems on the GMAT, if you use a formula to solve a problem more times than you can count on one hand, you are problem leaning on formulas too much. Finally, I get the feeling that your whole approach is very left-brain --- you like to have a list, have a recipe, have a clear set of steps to follow. If someone provides the clear set of steps, you can reliably follow them. BUT, perhaps when you have to discern a new pattern for yourself --- perhaps that's where you struggle. See this post: http://magoosh.com/gmat/2013/how-to-do- ... th-faster/ Finally, this last post is mostly for folks just starting out, but you may find a few helpful tips in here that you haven't seen elsewhere: http://magoosh.com/gmat/2013/how-to-stu ... gmat-math/

Let me know if you have any further questions. Mike

GREAT reply....on the magoosh site there's a sample problem here: http://gmat.magoosh.com/questions/100?u ... AlphaBetaM that I tried using the strategies you outlined. Worked out much better, because instead of just plugging in formula, I thought about how the two shapes related to each other and THEN used formulas once I was sure which ones I needed to select. I have a habit of making calculations I don't even need to when reading problems. Another problem I have is that once I start doing that, I miss details at the end of the question because I'm already trying to calculate areas/speed/whatever in my head.

When I was in high school my friends used to make a game out of seeing whether I could calculate the output of complex formulas in my head quicker than they could input it to their graphing calculators. Being able to do that is handy when needed, but in retrospect it made me lazy because I can brute force 90% of the problems I've come across, but that doesn't work in the least on the GMATs, it's like trying to ram my head through a brick wall. I always tested in the highest percentiles for abstract reasoning as well, but just being able to calculate things via formulas in my head always seemed quicker/easier. I'm going to start pouring through the site you linked to, hopefully I can retrain myself to start using some of that abstract thinking. A lot of the problems I have difficulty with are the ones with extremely intricate formulas on them. Given time constraints that should be a huge hint that there is some pattern that should make the answer obvious.

Maybe you can help with another issue I have, with wording of problems. Here's an example:

Among a group of 2,500 people, 35 percent invest in municipal bonds, 18 percent invest in oil stocks, and 7 percent invest in both municipal bonds and oil stocks. If 1 person is to be randomly selected from the 2,500 people, what is the probability that the person selected will be one who invests in municipal bonds and NOT in oils stocks?

(A) 9/50 (B) 7/25 (C) 7/20 (D) 21/50 (E) 27/50

Here's what I did wrong: I assumed that the 35% group, the 18% group, and the 7% group were all made up of different individuals, so I ended up selecting (C). In actuality you are supposed to subtract the 7% from the 35%, and then solve, getting (B) as an answer. I do this all. the. time. I'm never sure if when a question mentions groups like this whether I'm supposed to abstract something, or if the groups are distinct. This carries over to other problems too, anytime there are groups or factors without really detailed boundaries and specifics given I get tripped up. Other problems that list things, like this one which lists a number set: if-x-y-are-in-the-set-then-xy-is-also-in-the-set-160975.html I'm never sure if the variables mentioned are the only ones, or if there's others, you can actually see my reply there to that thread. I'm sure there's an article on your site somewhere for how to figure this stuff out, if you could link it that would be awesome.

Again, thank you so much for your reply, I'm going to start digging through those articles.

Re: Making no progress on PS questions [#permalink]
03 Oct 2013, 20:54

1

This post received KUDOS

Expert's post

AccipiterQ wrote:

Can someone help me figure out why I can't translate the formulas I'm learning here to other problems (for PS problems). I get about 95% of 600 level+ PS problems incorrect, but when I look at the solutions, they make perfect sense to me. Earlier someone linked me to a guide they made for when to use certain formula, and I get the examples he gives, but if you wait 10 minutes, and give me an identical problem, just with the numbers in the question changed, I can't do it. I don't understand why. I used to tutor people in calculus, advanced algebras, etc. But the GMAT questions are so far beyond anything I used there. I was hoping that I would be able to memorize the formulas for the GMAT questions as easily as I did calc/algebra/etc., but honestly I'm lost. I've been studying for weeks, and my score on the PS problems is still the same. So clearly I'm doing something wrong. I need help here, I want to get in the 730-760 range, and I think I'm pretty close, but if I'm getting about 19 out of every 20 PS problems incorrect (and honestly the ones I do get right I'm guessing) that's going to hurt.

The bad of GMAT - A mathematician may not do well in this test The good of GMAT - Anyone can do well in this test

As I am sure you know by now, GMAT is not a test of Math. It is a test of logic. If you think about it, it's logical, isn't it? GMAT score is used by MBA institutes which prepare you for the business environment - just how much Math do you think you need to use to run a business? Whatever little you need, you have calculators and computers for it. You need to prepare for things that machines cannot do - think. So GMAT tests your reasoning, your logic, your aptitude, your stamina, your ability to handle pressure, your ability to take decisions in a short span etc. Math and English provide a framework for testing these particular qualities. If there were a list of things that you could memorize to do well in GMAT, the test would fail since it would not be able to grade you on any of the above given things.

You need to develop skill to do well in GMAT and yes, your approach needs to be completely different. Throw away all your formula sheets. I am sure that the ones you need to know, you already do (e.g. Distance = Speed*Time). Focus on the problem given and how you need to manipulate the data to arrive at the answer. Do not think of a suitable formula. Even if you know a formula, imagine that you have forgotten it. Look for a way to solve from scratch. Do it for enough problems and soon you will be coming up with your own formulas. _________________

Re: Making no progress on PS questions [#permalink]
04 Oct 2013, 13:14

1

This post received KUDOS

Expert's post

AccipiterQ wrote:

Maybe you can help with another issue I have, with wording of problems. Here's an example:

Among a group of 2,500 people, 35 percent invest in municipal bonds, 18 percent invest in oil stocks, and 7 percent invest in both municipal bonds and oil stocks. If 1 person is to be randomly selected from the 2,500 people, what is the probability that the person selected will be one who invests in municipal bonds and NOT in oils stocks?

(A) 9/50 (B) 7/25 (C) 7/20 (D) 21/50 (E) 27/50

Here's what I did wrong: I assumed that the 35% group, the 18% group, and the 7% group were all made up of different individuals, so I ended up selecting (C). In actuality you are supposed to subtract the 7% from the 35%, and then solve, getting (B) as an answer. I do this all. the. time. I'm never sure if when a question mentions groups like this whether I'm supposed to abstract something, or if the groups are distinct. This carries over to other problems too, anytime there are groups or factors without really detailed boundaries and specifics given I get tripped up. Other problems that list things, like this one which lists a number set: if-x-y-are-in-the-set-then-xy-is-also-in-the-set-160975.html I'm never sure if the variables mentioned are the only ones, or if there's others, you can actually see my reply there to that thread. I'm sure there's an article on your site somewhere for how to figure this stuff out, if you could link it that would be awesome.

Again, thank you so much for your reply, I'm going to start digging through those articles.

Dear AccipiterQ, On the question you cite, always keep in mind that the magic words "AND" and "OR" automatically include elements from the separate individual groups. Think about it --- suppose I ask you, "Are you P?" and you say yes, and then I ask, "Are you Q?", and you say yes. That means you would be in the group P, the group Q, the group (P and Q), and the group (P or Q). The combination groups are built out of folks who have already answered the individual questions.

On the x & y & xy set, I already responded to your post on that page.

I would recommend reading carefully all the math articles on that blog I sent, and I also would recommend anything the brilliant Karishma recommends to you.

Understand, it's hard to answer questions about this stuff in the abstract. When you make a mistake of this genre on a particular question, find it posted on GC or post it in a new thread, and sent me a pm with the link, and I will be happy to comment.

Re: Making no progress on PS questions [#permalink]
04 Oct 2013, 17:41

VeritasPrepKarishma wrote:

AccipiterQ wrote:

Can someone help me figure out why I can't translate the formulas I'm learning here to other problems (for PS problems). I get about 95% of 600 level+ PS problems incorrect, but when I look at the solutions, they make perfect sense to me. Earlier someone linked me to a guide they made for when to use certain formula, and I get the examples he gives, but if you wait 10 minutes, and give me an identical problem, just with the numbers in the question changed, I can't do it. I don't understand why. I used to tutor people in calculus, advanced algebras, etc. But the GMAT questions are so far beyond anything I used there. I was hoping that I would be able to memorize the formulas for the GMAT questions as easily as I did calc/algebra/etc., but honestly I'm lost. I've been studying for weeks, and my score on the PS problems is still the same. So clearly I'm doing something wrong. I need help here, I want to get in the 730-760 range, and I think I'm pretty close, but if I'm getting about 19 out of every 20 PS problems incorrect (and honestly the ones I do get right I'm guessing) that's going to hurt.

The bad of GMAT - A mathematician may not do well in this test The good of GMAT - Anyone can do well in this test

As I am sure you know by now, GMAT is not a test of Math. It is a test of logic. If you think about it, it's logical, isn't it? GMAT score is used by MBA institutes which prepare you for the business environment - just how much Math do you think you need to use to run a business? Whatever little you need, you have calculators and computers for it. You need to prepare for things that machines cannot do - think. So GMAT tests your reasoning, your logic, your aptitude, your stamina, your ability to handle pressure, your ability to take decisions in a short span etc. Math and English provide a framework for testing these particular qualities. If there were a list of things that you could memorize to do well in GMAT, the test would fail since it would not be able to grade you on any of the above given things.

You need to develop skill to do well in GMAT and yes, your approach needs to be completely different. Throw away all your formula sheets. I am sure that the ones you need to know, you already do (e.g. Distance = Speed*Time). Focus on the problem given and how you need to manipulate the data to arrive at the answer. Do not think of a suitable formula. Even if you know a formula, imagine that you have forgotten it. Look for a way to solve from scratch. Do it for enough problems and soon you will be coming up with your own formulas.

Another amazing reply, thank you

gmatclubot

Re: Making no progress on PS questions
[#permalink]
04 Oct 2013, 17:41