GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 21 Oct 2018, 05:41

### 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

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

# A total of 9 women and 12 men reside in the 21 apartments that are in

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 50010
A total of 9 women and 12 men reside in the 21 apartments that are in  [#permalink]

### Show Tags

15 Dec 2014, 09:26
00:00

Difficulty:

5% (low)

Question Stats:

92% (01:03) correct 8% (01:02) wrong based on 76 sessions

### HideShow timer Statistics

Tough and Tricky questions: Word Problems.

A total of 9 women and 12 men reside in the 21 apartments that are in a certain apartment building, one person to each apartment. If a poll taker is to select one of the apartments at random, what is the probability that the resident of the apartment selected will be a woman who is a student?

(1) Of the women, 4 are students.
(2) Of the women, 5 are not students.

Kudos for a correct solution.

_________________
Manager
Joined: 10 Sep 2014
Posts: 98
Re: A total of 9 women and 12 men reside in the 21 apartments that are in  [#permalink]

### Show Tags

15 Dec 2014, 10:41
statement 1: sufficient
If 4 of the women are students, the chance of randomly selecting 1 among the 21 apartments is 4/21

statement 2: sufficient
If 5 of the women are not students, then 9-5=4 of the women are students. Same as above.

Intern
Joined: 13 Sep 2015
Posts: 1
Re: A total of 9 women and 12 men reside in the 21 apartments that are in  [#permalink]

### Show Tags

12 Mar 2016, 10:34
I thought that the correct answer is A.
The statement 2 claims that: of the women, 5 are not students. But, it does no mean that the other 4 are students. They could be workers, teachers, etc. if the other 4 are students, the probability is 4 / 21. If not, we do not know. So, statement 2 is not sufficient....
Manager
Joined: 03 Mar 2018
Posts: 182
Re: A total of 9 women and 12 men reside in the 21 apartments that are in  [#permalink]

### Show Tags

31 Mar 2018, 06:44
Quote:
A total of 9 women and 12 men reside in the 21 apartments that are in a certain apartment building, one person to each apartment. If a poll taker is to select one of the apartments at random, what is the probability that the resident of the apartment selected will be a woman who is a student?

(1) Of the women, 4 are students.
(2) Of the women, 5 are not students.

chetan2u
In Statement 2, How can we be so sure that the remaining 4 women are students?
_________________

Math Expert
Joined: 02 Aug 2009
Posts: 6971
Re: A total of 9 women and 12 men reside in the 21 apartments that are in  [#permalink]

### Show Tags

31 Mar 2018, 11:01
1
itisSheldon wrote:
Quote:
A total of 9 women and 12 men reside in the 21 apartments that are in a certain apartment building, one person to each apartment. If a poll taker is to select one of the apartments at random, what is the probability that the resident of the apartment selected will be a woman who is a student?

(1) Of the women, 4 are students.
(2) Of the women, 5 are not students.

chetan2u
In Statement 2, How can we be so sure that the remaining 4 women are students?

Hi...
When it comes to being a student, there are ONLY 2 possiblities - student or not a student.
So if 5 women are not students, the remaining 4 are of the other category- students.
May be within them out have people from US, India, France, UK etc but the number of women who are students will remain 9-5=4
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

GMAT online Tutor

Manager
Joined: 21 Jan 2018
Posts: 56
Location: India
GPA: 2.85
WE: Consulting (Consulting)
A total of 9 women and 12 men reside in the 21 apartments that are in  [#permalink]

### Show Tags

01 Apr 2018, 21:55
Bunuel wrote:

Tough and Tricky questions: Word Problems.

A total of 9 women and 12 men reside in the 21 apartments that are in a certain apartment building, one person to each apartment. If a poll taker is to select one of the apartments at random, what is the probability that the resident of the apartment selected will be a woman who is a student?

(1) Of the women, 4 are students.
(2) Of the women, 5 are not students.

Kudos for a correct solution.

Total Residents =21
No. of Women = 9
Let X be the no of women who are students.

Probability to select Woman P (Woman) = $$\frac{9}{12}$$
Probability of getting a Women who is student = $$\frac{P(Women)*X}{9}$$
P(WomanStudent) = $$\frac{9}{21}*\frac{X}{9}$$
P(WomanStudent) = X/21

Now X we can find from both statement 1 and 2 seperately

Therefore Option D
_________________

Regards ,
Dhruv
_________________
Kudos will encourage many others, like me.

Please Give +1 Kudos if you liked the post!!

Thanks

A total of 9 women and 12 men reside in the 21 apartments that are in &nbs [#permalink] 01 Apr 2018, 21:55
Display posts from previous: Sort by