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Re: Good Overlapping Set Problem [#permalink]
30 May 2010, 05:34

27

This post received KUDOS

Expert's post

Hussain15 wrote:

In a group of 80 college students, how many own a car?

(1) Of the students who do not own a car, 14 are male.

(2) Of the students who own a car, 42% are female.

(1) Of the students who do not own a car, 14 are male. Clearly insufficient.

(2) Of the students who own a car, 42% are female --> let # of students who own a car be x --> 0.42x= # of females who own a car. But 0.42x must be an integer, as it represent # of females. 0.42x=integer --> \frac{21}{50}x=integer --> x is a multiple of 50: 50, 100, 150, ... But x (# of students who own car) must also be less than (or equal to) 80. So x=50. sufficient.

Re: Good Overlapping Set Problem [#permalink]
14 Sep 2010, 06:39

Bunuel wrote:

Hussain15 wrote:

In a group of 80 college students, how many own a car?

(1) Of the students who do not own a car, 14 are male.

(2) Of the students who own a car, 42% are female.

(1) Of the students who do not own a car, 14 are male. Clearly insufficient.

(2) Of the students who own a car, 42% are female --> let # of students who own a car be x --> 0.42x= # of females who own a car. But 0.42x must be an integer, as it represent # of females. 0.42x=integer --> \frac{21}{50}x=integer --> x is a multiple of 50: 50, 100, 150, ... But x (# of students who own car) must also be less than (or equal to) 80. So x=50. sufficient.

Re: Good Overlapping Set Problem [#permalink]
16 Sep 2010, 10:33

Bunuel wrote:

Hussain15 wrote:

In a group of 80 college students, how many own a car?

(1) Of the students who do not own a car, 14 are male.

(2) Of the students who own a car, 42% are female.

(1) Of the students who do not own a car, 14 are male. Clearly insufficient.

(2) Of the students who own a car, 42% are female --> let # of students who own a car be x --> 0.42x= # of females who own a car. But 0.42x must be an integer, as it represent # of females. 0.42x=integer --> \frac{21}{50}x=integer --> x is a multiple of 50: 50, 100, 150, ... But x (# of students who own car) must also be less than (or equal to) 80. So x=50. sufficient.

Re: Good Overlapping Set Problem [#permalink]
16 Sep 2010, 16:33

Awesome question. I too thought the answer is E. That's why it's a good idea to set up equations because these things become plain as day when you write them out. Important to remember that all statements are true.
_________________

The Brain Dump - From Low GPA to Top MBA(Updated September 1, 2013) - A Few of My Favorite Things--> http://cheetarah1980.blogspot.com

Re: In a group of 80 college students, how many own a car? (1) [#permalink]
31 Dec 2012, 06:51

Hussain15 wrote:

In a group of 80 college students, how many own a car?

(1) Of the students who do not own a car, 14 are male.

(2) Of the students who own a car, 42% are female.

I am confident this question will never be tested in GMAT. There are two parts of my argument. First GMAT does tests 2-D table in a variety of ways. It also tests the two variable one equation where answers can be deduced sometime based on the constraints used, for example a 21c pencil and 23c pen bought for some amount may have only one solution as it has only one such possible combination etc. That leads me to thing why the creator here has combined the two and probably a tried a super trick question. But GMAT is not about such tricks. GMAT tests practical scenario, for example, two variable one equation leading to a unique solution is a well known optimazation problem and there are tons of those tested in high school algebra and in real world.

Second, I have never seen this sort of un-necessay tricks employed in any GMAT questions. Probably filtering mechanism through experimental question will always leads to non-consistent percentile.

Re: Good Overlapping Set Problem [#permalink]
01 Jan 2013, 00:53

Bunuel wrote:

Hussain15 wrote:

In a group of 80 college students, how many own a car?

(1) Of the students who do not own a car, 14 are male.

(2) Of the students who own a car, 42% are female.

(1) Of the students who do not own a car, 14 are male. Clearly insufficient.

(2) Of the students who own a car, 42% are female --> let # of students who own a car be x --> 0.42x= # of females who own a car. But 0.42xmust be an integer, as it represent # of females. 0.42x=integer --> \frac{21}{50}x=integer --> x is a multiple of 50: 50, 100, 150, ... But x (# of students who own car) must also be less than (or equal to) 80. So x=50. sufficient.

Answer: B.

I think since the answer is based on a fine point, that the number pf car owners has to be an integer, they need to have covered that angle well. But I think they did not. The integer mentioned above can be 0 and need not be positive. I am pointing this out because in a quantitative test, precision is important.
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