Manhattan 700-800 level

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 120
Joined: Mon Nov 07, 2011 10:54 pm
Location: Delhi
Thanked: 5 times

Manhattan 700-800 level

by bryan88 » Sun May 13, 2012 7:13 am
If there are x men and y women in a choir, and there are z more men than there are women in that choir, what is z?

(1) x² - 2xy + y² - 9 = 0

(2) x² + 2xy + y² - 225 = 0

User avatar
Master | Next Rank: 500 Posts
Posts: 385
Joined: Mon Apr 16, 2012 8:40 am
Location: Pune, India
Thanked: 186 times
Followed by:29 members

by aneesh.kg » Sun May 13, 2012 7:40 am
Given:
x = y + z
z = (x - y)
What is the value of z?
Since none of the statements contain 'z', we will look for finding the value (x - y).

Statement(1):
(x - y)^2 = 9
(x - y) = 3 or -3
-3 is ruled out. (because it is given that there are more men than women, so x > y)
(x - y) = 3 = z
SUFFICIENT

Statement(2):
(x + y)^2 = 225
(x + y) = 15 or -15
In any case, we're not getting (x - y) from this.
INSUFFICIENT

[spoiler](A)[/spoiler] is the answer
Aneesh Bangia
GMAT Math Coach
[email protected]

GMATPad:
Facebook Page: https://www.facebook.com/GMATPad