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M27-04

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M27-04  [#permalink]

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New post 16 Sep 2014, 01:26
1
25
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

28% (02:22) correct 72% (02:14) wrong based on 164 sessions

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Re M27-04  [#permalink]

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New post 16 Sep 2014, 01:26
7
11
Official Solution:


Tricky question.

(1) Of the astronauts who do NOT listen to Bach, 56% are male. If # of astronauts who do NOT listen to Bach is \(x\), then \(0.56x\) is # of males who do NOT listen to Bach. Notice that \(0.56x=\frac{14}{25}x\) must be an integer. Hence, \(x\) must be a multiple of 25: 25, 50, 75, ... But \(x\) (# of astronauts who do NOT listen to Bach) must also be less than (or equal to) 35. So \(x\) can only be 25, which makes # of astronauts who do listen to Bach equal to \(35-25=10\). Sufficient.

(2) Of the astronauts who listen to Bach, 70% are female. Now, if we apply the same logic here we get that, if # of astronauts who listen to Bach is \(y\), then \(0.7y\) is # of females who listen to Bach: \(0.7y=\frac{7}{10}y\) must be an integer. Hence, it must be a multiple of 10, but in this case it can take more than 1 value: 10, 20, 30. So, this statement is not sufficient.


Answer: A
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New post 11 Aug 2016, 21:51
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Excellent Question.
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New post 17 Aug 2016, 04:33
I think this is a high-quality question and I agree with explanation. Very good question
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New post 29 Oct 2016, 09:28
For this question, I believe it is helpful to draw a "grid", sort of like this:

Bach NotBach Total

Male

Female

Total >=1 35

And then fill in with the informations from statements 1 and 2. That's how I figured that the 0.56*x and 0.7*x had to be integers.
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New post 31 Oct 2016, 06:00
How to quickly convert the decimal to fraction such as these?
0.56X = [14][/25]X
Please help.
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New post 31 Oct 2016, 06:06
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New post 01 Nov 2016, 16:18
I think this is a high-quality question and the explanation isn't clear enough, please elaborate. "If at least one astronaut does NOT listen to Bach"

1. What would have happened if the question stem did not have these words?? 2. what is the significance of these words?
3. How would it change the answer
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New post 20 Aug 2017, 20:51
Bunuel wrote:
Official Solution:


Tricky question.

(1) Of the astronauts who do NOT listen to Bach, 56% are male. If # of astronauts who do NOT listen to Bach is \(x\), then \(0.56x\) is # of males who do NOT listen to Bach. Notice that \(0.56x=\frac{14}{25}x\) must be an integer. Hence, \(x\) must be a multiple of 25: 25, 50, 75, ... But \(x\) (# of astronauts who do NOT listen to Bach) must also be less than (or equal to) 35. So \(x\) can only be 25, which makes # of astronauts who do listen to Bach equal to \(35-25=10\). Sufficient.

(2) Of the astronauts who listen to Bach, 70% are female. Now, if we apply the same logic here we get that, if # of astronauts who listen to Bach is \(y\), then \(0.7y\) is # of females who listen to Bach: \(0.7y=\frac{7}{10}y\) must be an integer. Hence, it must be a multiple of 10, but in this case it can take more than 1 value: 10, 20, 30. So, this statement is not sufficient.


Answer: A


Hi Bunuel,

I have one doubt. Can you please help to clarify.

Its given in Option 1 that "Of the astronauts who do NOT listen to Bach, 56% are male" & from our calculation, its been found that the no is 25. Now we also need to consider the No of Females who do NOT listen to Bach. Without considering that , how are we arriving at the conclusion that :-

"# of astronauts who do listen to Bach equal to 35-25=10 " ?

Can you please clarify further.
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New post 21 Aug 2017, 03:37
ran787 wrote:
Bunuel wrote:
Official Solution:


Tricky question.

(1) Of the astronauts who do NOT listen to Bach, 56% are male. If # of astronauts who do NOT listen to Bach is \(x\), then \(0.56x\) is # of males who do NOT listen to Bach. Notice that \(0.56x=\frac{14}{25}x\) must be an integer. Hence, \(x\) must be a multiple of 25: 25, 50, 75, ... But \(x\) (# of astronauts who do NOT listen to Bach) must also be less than (or equal to) 35. So \(x\) can only be 25, which makes # of astronauts who do listen to Bach equal to \(35-25=10\). Sufficient.

(2) Of the astronauts who listen to Bach, 70% are female. Now, if we apply the same logic here we get that, if # of astronauts who listen to Bach is \(y\), then \(0.7y\) is # of females who listen to Bach: \(0.7y=\frac{7}{10}y\) must be an integer. Hence, it must be a multiple of 10, but in this case it can take more than 1 value: 10, 20, 30. So, this statement is not sufficient.


Answer: A


Hi Bunuel,

I have one doubt. Can you please help to clarify.

Its given in Option 1 that "Of the astronauts who do NOT listen to Bach, 56% are male" & from our calculation, its been found that the no is 25. Now we also need to consider the No of Females who do NOT listen to Bach. Without considering that , how are we arriving at the conclusion that :-

"# of astronauts who do listen to Bach equal to 35-25=10 " ?

Can you please clarify further.


x (25) in the solution denotes the number of astronauts who do not listen to Bach, x is NOT the number of male astronauts who listen to Bach.
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Re: M27-04  [#permalink]

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New post 17 Sep 2017, 10:10
Bunuel wrote:
Official Solution:


Tricky question.

(1) Of the astronauts who do NOT listen to Bach, 56% are male. If # of astronauts who do NOT listen to Bach is \(x\), then \(0.56x\) is # of males who do NOT listen to Bach. Notice that \(0.56x=\frac{14}{25}x\) must be an integer. Hence, \(x\) must be a multiple of 25: 25, 50, 75, ... But \(x\) (# of astronauts who do NOT listen to Bach) must also be less than (or equal to) 35. So \(x\) can only be 25, which makes # of astronauts who do listen to Bach equal to \(35-25=10\). Sufficient.

(2) Of the astronauts who listen to Bach, 70% are female. Now, if we apply the same logic here we get that, if # of astronauts who listen to Bach is \(y\), then \(0.7y\) is # of females who listen to Bach: \(0.7y=\frac{7}{10}y\) must be an integer. Hence, it must be a multiple of 10, but in this case it can take more than 1 value: 10, 20, 30. So, this statement is not sufficient.


Answer: A



Wonderfulllll! This is such an awesome question. Love the explanation as well. The important point to note here is that we are dealing with people, so we have to take care that we are dealing with integers. First sight at the option choices indicate that the answer is E. but once you drill deeper, you realize that answer is A. Excellent question.
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New post 06 Mar 2018, 11:14
can you provide more questions of this type to practice
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New post 20 Mar 2018, 19:33
This question popped up as very first question in GMAT Club tests and had me stumped. I answered E and it was wrong. After the explanation from bunuel, i understood A is the answer. Excellent Question
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New post 12 Sep 2018, 08:26
One of the best questions on GMAT Club.
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New post 12 Dec 2018, 13:03
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Great Question! My friend gave gmat exam last week. He scored q50. He told me that he was majorly tested more on Arithmetic. He got very few and easy questions of inequalities, numbers, geometry, pnc and probability. Exam comprised of percentages and profit loss questions and general arithmetic.
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New post 12 Dec 2018, 13:04
bhavik1995 wrote:
Great Question! My friend gave gmat exam last week. He scored q50. He told me that he was majorly tested more on Arithmetic. He got very few and easy questions of inequalities, numbers, geometry, pnc and probability. Exam comprised of percentages and profit loss questions and general arithmetic.


Now confused that are these questions even worth practicing?
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New post 25 Feb 2019, 12:14
I think this is a high-quality question and I agree with explanation.
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Re M27-04   [#permalink] 25 Feb 2019, 12:14
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