It is currently 20 Oct 2017, 07:57

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

The Ultimate Q51 Guide [Expert Level]

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 29 Jun 2016, 20:29
Expert's post
1
This post was
BOOKMARKED
This is also a type of question related to common mistake type 4(A)
When 25 integers are there such that their average (arithmetic mean) is 100, is their median equal to 100?
1) They are consecutive
2) The average (arithmetic mean) of the greatest number and the smallest number of them is 100
There are 2 variables in the question. Hence, C can be the answer. Yet, since this is an integer question, we have to apply common mistake type 4(A). Hence, this makes A the answer.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 01 Jul 2016, 02:31
This is also a 50-51 level question and is related to the common mistake type 4(A)
When 25 integers are there such that their average (arithmetic mean) is 100, is their median equal to 100?
1) They are consecutive
2) The average (arithmetic mean) of the greatest number and the smallest number of them is 100

There are 2 variables in the question. Hence, C could be the answer. However, since this is an integer question, we have to apply the common mistake type 4(A). Then, we can see that A is the correct answer.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 03 Jul 2016, 05:59
Below is a type of common mistake type 4(A) questions. Many integer questions are related to this mistake type.
(ex 3) If x is integer and |x|+x<4, what is the value of x?
1) x>0
2) x<-2
If we modify the original condition and the question, we get 2x<4, x<0 when x>0. Since x<0 is always true, we get x<2. Since there is one variable (x), there is a high chance that D is the correct answer.
In case of con 1), as 0<x<2, x=1. The answer is unique and the condition is sufficient.
In case of con 2), since x<-2, the answer is not unique and the condition is not sufficient. Hence, the correct answer is A.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 04 Jul 2016, 23:59
A Geometry question can be difficult as well
(ex 6) A rectangular iron plate is 12 feet by 8 feet. We can make a right circular cylinder by rolling the length side of the plate or the width side of the plate. If the cylinder’s volume is at its greatest, which one of the length or the width of the iron plate is the circumference of the cylinder and what is the difference between 2 volumes of cylinders made by rolling?
A. the circumference is 8, the difference is 54/π
B. the circumference is 8, the difference is 96/π
C. the circumference is 12, the difference is 84/π
D. the circumference is 12, the difference is 96/π
E. the circumference is 12, the difference is 86/π
==> As the number increases fast when it is squared, the volume increases faster when it is being rolled at 12-inches side. Hence, from 2πr=12, we get r=6/π. Hence, π(6/π)2(8)=288/π. The volume of the cylinder rolled at the 8-inches side is – from 2πr=8, we get r=4/π – π(4/π)2(12)=192/π. The difference is 288/π-192/π=96/π. Hence, the correct answer is D.
Answer: D
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 05 Jul 2016, 21:21
If x and y are integers, is x+y an even?
1) x-y is an even
2) y is an odd
Above question is also a 50-51 level question. Both C and A can be correct. Hence, this is a typical common mistake type 4(A) question.
Answer: A
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

Expert Post
1 KUDOS received
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [1], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 06 Jul 2016, 17:05
1
This post received
KUDOS
Expert's post
As always, questions combined with the mistake type 3 and 4 are given. Let's have a look at the example below. This is a very recent question, which also belongs to the mistake type 4(A). This question is on the level of score 50-51. You should be able to tackle a question like this. In addition, you should be aware of relation between approach method to variables and the mistake types.
(ex 1) (integer) If x and y are integers, is xy an even?
1) y=4x
2) x=odd
Both C and A can be answers. This is a 50-51 level question. From con 1), y=4x is always even. Hence, the condition is sufficient and the answer is A.
Answer: A
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [1], given: 0

Expert Post
1 KUDOS received
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [1], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 08 Jul 2016, 21:53
1
This post received
KUDOS
Expert's post
1
This post was
BOOKMARKED
What is the median number of cloths sold in the last 11 days?
1) 30 cloths are sold every day in the last 6 days
2) The total number of cloths sold was 400 in the last 11 days.

This is a typical common mistake type 4(A) question. The answer can either be C or A. The final correct answer is A.
Answer: A
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [1], given: 0

Expert Post
1 KUDOS received
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [1], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 11 Jul 2016, 00:53
1
This post received
KUDOS
Expert's post
2
This post was
BOOKMARKED
Is a>b?
1) a>|b|
2) |a|>b
This is a common mistake type 4(A) question in which both C and A can be an answer. We apply the common mistake type 4(A) because this is an absolute question, which is one of key questions. In other words, in case of con 1), from a>|b|≥b, we get a>b. Hence, the answer is yes and the condition is sufficient. Thus, the correct answer is A.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [1], given: 0

Expert Post
1 KUDOS received
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [1], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 12 Jul 2016, 19:11
1
This post received
KUDOS
Expert's post
1
This post was
BOOKMARKED
Below is common mistake type 4(B) question.
If x and y are integers, is x2+xy an even?
1) x=even
2) y=odd
There are 2 variables in the original condition. Hence, there is a high chance that C is the correct answer. From 1) and 2), C is certainly an answer. However, since it is one of key questions, we should apply the common mistake type 4(A). We can see that con 1) gives the answer that is ‘yes’ too easily because x(x+y)=even(x+y)=even. However, since con 2) is difficult, we should apply the common mistake type 4(B). Then, the correct answer is D.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [1], given: 0

Intern
Intern
avatar
Joined: 05 Dec 2015
Posts: 7

Kudos [?]: 5 [0], given: 11

Location: United States
WE: Military Officer (Military & Defense)
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 14 Jul 2016, 21:06
Great Thread!

What GMAT club tags would be included in "Integer Properties?" Divisibility and multiples... what else?

Kudos [?]: 5 [0], given: 11

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 18 Jul 2016, 04:32
There are many difficult PS questions nowadays.
(ex 5) *(integer) 40,195*26*10,082 is approximation of which of the followings?
A. 108 B. 109 C. 1010 D. 1011 E. 1012
40,000*25*10,00=1010. Hence, the correct answer is C
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 24 Jul 2016, 02:55
If m, n are positive integers, what is the unit digit of 7^(4m+2)+n?
1) m=1
2) n=2
Since there are 2 variables in the original condition, there is a high chance that C is the correct answer. Even though C is the correct answer, we have to apply the common mistake type 4(A) because it is one of key questions, integer question. From con 2), the units digit of 7^(4m+2) is always 4. Hence, we only have to know the value of n. Thus, the condition is sufficient and the correct answer is B.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 25 Jul 2016, 05:58
If |a+1|=|b-1|, a+b=?
1) a>b
2) a=b-1

Since there are 2 variables and 1 equation in the original condition, there is a high chance that D is the correct answer. The correct answer indeed is D according to the common mistake type 4(B).
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

1 KUDOS received
Manager
Manager
User avatar
B
Joined: 24 Jun 2016
Posts: 246

Kudos [?]: 43 [1], given: 13

Location: Viet Nam
Schools: Booth '19
GMAT 1: 770 Q60 V60
GPA: 4
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 25 Jul 2016, 10:27
1
This post received
KUDOS
MathRevolution wrote:
From con 2), the units digit of 7^(4m+2) is always 4.


I don't know what con 2) is, but the units digit of an odd integer can never be 4.

7^(4m+2) always has a digits unit of 9.

Posted from my mobile device
_________________

Offering top quality online and offline GMAT tutoring service in Vietnam, Southeast Asia, and worldwide.

$50/hour as of February 2017.


http://www.facebook.com/HanoiGMATtutor
HanoiGMATTutor@gmail.com

Kudos [?]: 43 [1], given: 13

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 25 Jul 2016, 19:45
As always, questions combined with the mistake type 3 and 4 are given. Let's have a look at the example below. This is a very recent question, which also belongs to the mistake type 4(A). This question is on the level of score 50-51. You should be able to tackle a question like this. In addition, you should be aware of relation between approach method to variables and the mistake types.
(ex 1) (integer) If m is an integer, is m an even?
1) m/2=integer
2) m=-m
Both C and D can be an answer. Applying the common mistake type 4(B), the correct answer is D.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 26 Jul 2016, 18:38
Becareful on the common mistake type 4(B)
If x and y are integers, is xy an even?
1) x=even
2) y=odd
There are 2 variables in the original condition and there is a high chance that C is the correct answer. Using 1) and 2), C is the correct answer. However, since this is one of key questions, con 1) is always yes. The condition is sufficient and the correct answer is A.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

Expert Post
1 KUDOS received
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [1], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 31 Jul 2016, 09:06
1
This post received
KUDOS
Expert's post
Are the median and the average (arithmetic mean) of m, n, and k are the same?
1) n is the average (arithmetic mean) of m, n, and k
2) m+n<k

This is a common mistake type 4(A) question in which both C and A can be an answer. The correct answer is A.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [1], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 04 Aug 2016, 04:53
This is a difficult inequality question.
(ex 6) *(inequality) If 0.01<a<0.02, 5,000<b<10,000, which of the following can be the value of (1/a2)+(1/b2)?
A. 0.2 B. 0.5 C. 750 D. 525 E. 7250

Answer: E
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

Expert Post
1 KUDOS received
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [1], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 07 Aug 2016, 17:57
1
This post received
KUDOS
Expert's post
This is a 50-51 level question

(ex 7) *(integer) What is the greatest common divisor of positive integers n and m?
1) n=1
2) m=n+1
There are 2 variables in the original condition (m, n). In order to match the number of variables and the number of equations, we need 2 equations. Hence, there is a high chance that C is the correct answer. Using 1) and 2), C is the correct answer. However, we have to utilize the common mistake type 4(B) since it is an integer question. The correct answer is D.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [1], given: 0

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2895 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: The Ultimate Q51 Guide [Expert Level] [#permalink]

Show Tags

New post 08 Aug 2016, 18:28
Please remember that DS questions will determine a score of 51 and also important are common mistake type questions.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2895 [0], given: 0

Re: The Ultimate Q51 Guide [Expert Level]   [#permalink] 08 Aug 2016, 18:28

Go to page   Previous    1   2   3   4   5   6   7   8   9   10   11  ...  18    Next  [ 358 posts ] 

Display posts from previous: Sort by

The Ultimate Q51 Guide [Expert Level]

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  

Moderator: HiLine



GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.