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.

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

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