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Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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Furthermore, complicated question with ratio are given. Let’s have a look at the question below.

(ex 5)80 percent of all the toys are made from Asia and 35 percent are made from Europe. What percent of all the toys are made from only Asia or Europe?
1) 30 percent of all the toys are made from both Asia and Europe.
2) 15 percent of all the toys are made from neither Asia nor Europe.

The above question is “2 by 2” question. There is 1 variable, which makes D the answer.
This type of question is frequently given on GMAT
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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As always, questions combined with the mistake type 3 and 4 are evolving. Let’s have a look at the question below. This is a very recent question, which also belongs to the mistake 4 and at the level of scoring 50-51. You have to be strong on a question like this. You should keep the relation between method of variable approach and the mistake types in mind.

(ex 1) If x, y are integers, is x^2+9x+y an even number?
1) x=15
2) y=10

The answer for the question is C but also B, which is a conventional question at level of scoring 50-51. You should be able to tackle a question like this. Be very cautious on integer or statistics questions, which make C the answer.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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Plus, inequality questions combined with the mistake type 4(B) are often given, which are at level of 50-51.

(ex 2 If m<n, is m2>mn?
1) m<0
2) n<0

In case of the above question, when you modify the question, m<0?, which makes it easy to solve 1). In case of 2), in n<m<0, it is yes and sufficient. Thus, D is the answer. This type of question is also at level of a score 50.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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As always, advanced questions like combined questions of the mistake type 3 and 4 are frequently given. Let's have a look at the recent question. It also belongs to the mistake type 4(A), which is at level of score 50-51. You have to be strong on this type of question and know the relation between method of variable approach and the mistake types.

(ex 1) If x, y are integers, is x^2+9x+y an even number?

1) x=15
2) y=10

In this question, not only is C the answer but also B, which is a typical question at level of score 50-51. You should be able to tackle a question like this. Focus on integer or statistics questions, which make C the answer.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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In addition, the mistake type 4(A) questions related to our life are given at level of score 50-51. In a case of the question below, the answer is A if you modify the question.

(ex 3) Machine X is taken 30 minutes for preparing to work and machine Y is taken 20 minutes for warming up before driving machines. The work rate of machine X is 40 parts per 1 minute and machine Y is 30 parts per 1 minute. Is the total time taken to work including preparing time of machine X smaller than that of machine Y?

1) The total task is more than 1,200 parts.
2) The total task is less than 1,800 parts.

Therefore, when you face with questions related to real life, approach them very cautiously.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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As always, questions combined with the mistake type 3 and 4 are evolving and often given. The below question is recent, which also belongs to the mistake type 4(A) at level of score 50-51. You should be able to solve this type of question and know the relation between method of approach to variables and the mistake types.

(ex 1) If x and y are different prime numbers, and n is a positive integer, what is the factors’ number of x(y^n)?

1) xy=21
2) n=2

The answer is C but also B, which is a typical question at level of score 50-51. You have to be strong with a question like this. Be cautious on integer or statistics questions, which make C the answer. Especially, be aware of the word "different" when questions with factor or prime factors are given.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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Besides, questions trembling students like the below still have been given on exams. The below question adapts the concept of an absolute value is an length of two points. This type of question has continuously appeared since 10 years ago. Sure, as there are 3 variables, the answer is E.

(ex 3) Is |x-y|<|x-z|?
1) |y|<|z|
2) x<0

It might look simple seemingly though it can be overwhelming when you actually face it in an exam. Approach this type of question after fully comprehending the method of approach to variables.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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As always, more developed questions combined with the mistake types 3 and 4 appear on GMAT. Look at the question below. This is a very recent one, which also belongs to the mistake type 4(A) at level of score 50-51. You should be able to tackle this type of question. Be aware of a relation between the method of approach to variable and the mistake types.

(ex 1) What is the median of 5 numbers?
1) They have 5 and 15
2) 3 of them are 10 each

In this question, the answer is C but also B, which is a typical question at level of 50-51. You have to be strong with this type of question. Focus on integer or statistics questions that make C the answer.
_________________

Originally posted by MathRevolution on 01 Apr 2016, 08:11.
Last edited by MathRevolution on 11 Apr 2016, 18:32, edited 1 time in total.
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

### Show Tags

As usual, developed questions combined with the mistake types 3 and 4 appear on GMAT. Let's look at the question below. This is a recent question, which also belongs to the mistake type 4(A) at level of score 50-51. You have to excel at the question like this, and also comprehend the relation between method of variable approach and the mistake types.

(ex 1) Is the range of a, b, c, and d greater than 7?
1) c-a=4, a-d=4
2) c-b=7

The answer is C but also A, which is a typical question at level of score 50-51. You should focus on integer or statistics questions that make C the answer.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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Also, this question is related to the mistake type 4(A). In this case, when number and ratio are given in a question, it is most likely that ratio can be the answer.

(ex 2)A certain company sells pencils in package and its sale price is not changed for a special sales period. But if the pencils’ number in one package is reduced, by what percent the unit sale price of pencils in one package increased?

1) The sale price per one package is \$8
2) The reduced number of pencils in one package is 20 percent of the original number

In this case, B which is ratio is the answer. This type of question is at level of score 50-51
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

### Show Tags

As always, more developed questions combined with the mistake types 3 and 4 appear on GMAT. Look at the question below. This is a very recent one, which also belongs to the mistake type 4(A) at level of score 50-51. You should be able to tackle this type of question. Be aware of a relation between the method of approach to variable and the mistake types.

(ex 1) What is the median of 5 numbers?
1) They have 5 and 15
2) 3 of them are 10 each

In this question, the answer is C but also B, which is a typical question at level of 50-51. You have to be strong with this type of question. Focus on integer or statistics questions that make C the answer.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

### Show Tags

As always, more developed questions combined with the mistake types 3 and 4 appear on GMAT. Look at the question below. This is a very recent one, which also belongs to the mistake type 4(A) at level of score 50-51. You should be able to tackle this type of question. Be aware of a relation between the method of approach to variable and the mistake types.

(ex 1) What is the median of 5 numbers?
1) They have 5 and 15
2) 3 of them are 10 each

In this question, the answer is C but also B, which is a typical question at level of 50-51. You have to be strong with this type of question. Focus on integer or statistics questions that make C the answer.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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Plus, this highly advance question is related to daily life. You also should be able to tackle PS questions.

There are 4 bottles with the same number balls m respectively. If balls from the only 1-st bottle are moved to the other 3 bottles and finally the ratio of the numbers of balls of the bottles is 1 to 6 to 5 to 4, does the moved balls represent in terms of m?

A. m/4 B. m/2 C. 3m/4 D. m E. 4m/5

It might seem simple though this can be very burdensome. You shouldn’t deal with PS question with disregard.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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In addition, integer questions are still frequently given.
Let's have a look at the question below.

(ex 5) If the first 20 positive even numbers’ sum is 420, what is the first 20 positive odd numbers’ sum?

A. 210
B. 240
C. 320
D. 360
E. 400

-> Even numbers are always bigger by 1 and there are 20 of them, which makes a difference by 20.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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Furthermore, the below question is an advanced question related to real life. You also have to be strong with a PS question like this.

(ex 3) one apple is 1pound per \$1. If the apple is peeled off and cored, 1/5 of the original apple's weight is off. Then the peeled and cored apple can be apple pie and 2cups of apple juice made by a blender come from such apple 1 pound. If such 3 cups of apples juice can make one apple pie, how much money it needs to make p apple pies, in dollars?

A. 2p
B. 15p/8
C. 8p/15
D. 2p/3
E. 3p/2

It might seem simple, but it can be challenging when you actually face this type of question on actual GMAT
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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Moreover, highly advanced integer questions are frequently given.

(ex) For positive integers n, k, f(n) is the remainder when n is divided by k. Is k>10?

1) f(k+32) = 8
2) f(k+42) = 6

In this case, the answer is B. You must have a solid concept of integer questions.
For 1), k=12,24 -> always yes and sufficient.
For 2), k=9 no, 12 yes -> not sufficient.

_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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Also, highly advance integer questions are frequently given.

We define “A mod n” as the remainder when A is divided by n. What is the value of “A mod 6”?

1) A mod 3=A mod 12
2) A mod 4=2

In this case, the answer is C. You have to have a solid concept of integer questions.
For 1), A mode 6=1,2, it is not unique and not sufficient.
For 2), A mode 6=0,2, it is not unique and not sufficient.
When 1) & 2), only A mode 6=2 is derived, which is unique and sufficient.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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As always, there are some advanced questions that are combined with the Common Mistake Type #3 and #4. Let’s have a look at the example below. This is a very recent type of questions, which also belongs to the mistake type 4(A). Since such types of questions appear in the level of score 50-51, you should be able to get them right for high scores. To this end, you should be aware of the relationship between the Variable Approach Method and the Common Mistake Types.
If the average (arithmetic mean) height of John, Tom and Jack is 1.70m, what is the median height of them?

1) The height of Tom is 1.65m.
2) The height of Jack is 1.70m

The answer to the above question is C but also B at the same time. This is a typical question that appears in the level of score 50-51. For high scores, you should be able to tack these types of questions. Focus on integer or statistics questions, which can make C an answer!
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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Some of difficult questions are related to our daily lives. You need to get them right for the perfect 51.
A bank has a number of coins which equals \$3.35 in total. There are only 2 types of coins: \$0.25 each and \$0.1 each. What is the remainder when the number of \$0.1 coins is divided by 5?
I. 0 II. 1 III. 2
A. I only B. II only C. I & II only D. I & III only E. I, II & III

This type of questions seems simply, but they are rather quite challenging. We call this type of questions as hidden integer questions.
_________________
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8267
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: The Ultimate Q51 Guide [Expert Level]  [#permalink]

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As always, the more advanced questions combined with the Common Mistake Type 3 and 4 frequently appear in the GMAT Math. Let's have a look at the question below. It is one of the most current type of the question. This question can also be described as the question involving Common Mistake Type 4(B), which appears in the level of score 50-51. You have to be very confident with questions like this. You have to know the relationship between Variable Approach Method and the mistake types.

The probability that event A occurs is 0.4 and the probability that event B occurs is 0.8. What is the probability that event A occurs but not event B?
1) Event A and event B are independent.
2) The probability that neither event A nor event B occurs is 0.32.

From the original condition, we only have to know P(A∩B). Hence, there is only 1 variable in the original condition, making D the mostly likely answer. Using the condition 1) and the condition 2), we can see the condition 1)=the condition 2). Hence, D is the correct answer.
_________________ Re: The Ultimate Q51 Guide [Expert Level]   [#permalink] 10 May 2016, 19:42

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# The Ultimate Q51 Guide [Expert Level]

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