If 2 different representatives are to be selected at random : DS Archive
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 16 Jan 2017, 11:48

### 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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# If 2 different representatives are to be selected at random

Author Message
Intern
Joined: 05 Oct 2007
Posts: 16
Followers: 0

Kudos [?]: 49 [0], given: 0

If 2 different representatives are to be selected at random [#permalink]

### Show Tags

30 Oct 2007, 10:13
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

### HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

If 2 different representatives are to be selected at random from a group of 10 employees and if p is the probability that both representatives selected will be women, is p > 1/2
(1) More than 1/2 of the 10 employees are women.
(2) The probability that both representatives selected will be men is less than 1/10.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

Pls explain.
Intern
Joined: 30 Oct 2007
Posts: 9
Followers: 0

Kudos [?]: 18 [0], given: 0

### Show Tags

31 Oct 2007, 07:33

and i hv attached the explanation to the file pls check
Attachments

E.doc [26 KiB]

CEO
Joined: 29 Mar 2007
Posts: 2583
Followers: 19

Kudos [?]: 420 [0], given: 0

### Show Tags

01 Nov 2007, 12:58
rags wrote:
If 2 different representatives are to be selected at random from a group of 10 employees and if p is the probability that both representatives selected will be women, is p > 1/2
(1) More than 1/2 of the 10 employees are women.
(2) The probability that both representatives selected will be men is less than 1/10.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

Pls explain.

S1: Don't bother w/ factorials, least for me, b/c it confused me at first.

Since there are 10 ppl: lets take the two extremes. Women>5.

So Case1: W=6
Case 2: W=9

6/10*5/9=30/90=1/3 P is not greater than 1/2

9/10*8/9 --> 72/90. P is greater than 1/2

Insuff.

S2:

let M equal the number of men.

M/10*(M-1)/9 < 1/10

(M^2-M)/90 <1> 10M^2-10M< 90 divide by 10 and subtract the 9.

M^2-M-9<0> (M - X ) (M + Y ) We know X must be greater than Y to produce -M. Just make some estimate values for X and Y b/c trying to solve exactly will take too long. We know X and Y must be near 3. So lets try -3.5 and 2.5 This will sum to -M and the product of these numbers is close to 9.

So (M-3.5)(M+2.5) M<3> 42/90. Close but not greater than 1/2.

M=1 then W=9. 9/10 *8/9 --> 72/90

Insuff.

taking these statements together adds nothing new and you shouldn't have to test further to realize this.

Ans E.
Re: DS - Probability   [#permalink] 01 Nov 2007, 12:58
Display posts from previous: Sort by