BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Probability - Columbus elementary school

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

Probability - Columbus elementary school

by Brent@GMATPrepNow » Sun Dec 28, 2008 11:10 am
If a child is randomly selected from Columbus elementary school, what is the probability that the child will be a boy?

(1) If 25 boys are removed from the school, the probability of selecting a boy will be 0.75
(2) There are 35 more boys than girls
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Source: — Data Sufficiency |
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Sun Dec 28, 2008 11:15 am
Hope I dint fall in to the trap.

Is it C)?

x->boys
y->girls

Stmt I

x+75 = 3y

Stmt II

y = x-35

Together solve for x and y

(If I did fall in to the trap then its between A and C)
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Sun Dec 28, 2008 12:42 pm
The answer is, indeed, C.
Nice work, cramya!
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Sun Dec 28, 2008 12:47 pm
Thanks to you for coming back after the christmas break and posting some good questions!

Wish u a happy new year!
Top
Legendary Member
Posts: 621
Joined: Wed Apr 09, 2008 7:13 pm
Thanked: 33 times
Followed by:4 members

by vittalgmat » Sun Dec 28, 2008 8:20 pm
Hi Cramya,
I am getting a different eqn in stmt 1.
here is my approach. let me know if something is wrong.

(B - 25) / (B -25 +G) = 3/4

-> 4B - 100 = 3B -75 +3G
-> 4B-3B = 100-75 +3G
-> B = 25 +3G
-> B -25 = 3G

However, this does not affect the final result.
Top
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Sun Dec 28, 2008 8:23 pm
Vittal, Urs is correct. There should be a -25 in the numerator
Top
Post new topic Post Reply
• Page 1 of 1