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please help, I really don't understand it.... a total of 9 women and 12 men reside in the 21 apartment that are in a certain apartment building, one person to each apartment. If a pool taker is to select one of the apartments at random, what is the probability that the resident of the apartment selected will be a women who is a student? 1) of the women, 4 are student 2) of the women, 5 are not student the answer is B looks easy, but I don't understand why B thanks in advance

Re: data sufficiency [#permalink]
03 Jul 2008, 04:01

Zaur wrote:

please help, I really don't understand it.... a total of 9 women and 12 men reside in the 21 apartment that are in a certain apartment building, one person to each apartment. If a pool taker is to select one of the apartments at random, what is the probability that the resident of the apartment selected will be a women who is a student? 1) of the women, 4 are student 2) of the women, 5 are not student the answer is B looks easy, but I don't understand why B thanks in advance

Re: data sufficiency [#permalink]
03 Jul 2008, 04:02

Seems strange to me too. I’d say St1 and St2 are equivalent – because if 5 women are not students, then, clearly, 9-5=4 are, and vice versa. So it should be D...

Re: data sufficiency [#permalink]
03 Jul 2008, 04:14

source? to be honest, I don't know, it is a test book made out on the basis of OG, Kaplan..... so, no way to understand from where it is may be it is a mistake....

Re: data sufficiency [#permalink]
03 Jul 2008, 08:14

Answer is D. I remember this from MGMAT.

1) of the women, 4 are student 2) of the women, 5 are not student

Since we know that there are 21 people, there are 21 choices. Ignore the men.

1) If 9 are women, and 4 are students, there are 4/9 students, or 4/21 that are women and students. 2) If 5 women are not students, then that means the remaining 4 students are women, so 4/21 again.

gmatclubot

Re: data sufficiency
[#permalink]
03 Jul 2008, 08:14

I couldn’t help myself but stay impressed. young leader who can now basically speak Chinese and handle things alone (I’m Korean Canadian by the way, so...