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

Redeem

Chess

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Legendary Member
Posts: 866
Joined: Mon Aug 02, 2010 6:46 pm
Location: Gwalior, India
Thanked: 31 times

Chess

by goyalsau » Mon Dec 20, 2010 7:51 am
In a chess competition involving some boys and girls of a school, every student had to play exactly one game with
every other student. It was found that in 45 games both the players were girls, and in 190 games both were boys. The
number of games in which one player was a boy and the other was a girl is


I. 200
2. 216
3. 235
4. 256
5. 171

According to me Answer is 171, What do you think Guys.
Saurabh Goyal
[email protected]
-------------------------


EveryBody Wants to Win But Nobody wants to prepare for Win.
Top
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 161
Joined: Mon Apr 05, 2010 9:06 am
Location: Mumbai
Thanked: 37 times

by 4GMAT_Mumbai » Mon Dec 20, 2010 7:59 am
Hi,

If both players were girls in 45 games; then there are 10 girls

If both players were boys in 190 games; then there are 20 boys.

Hence, there are 200 games involving a boy and a girl.

PS ... Perhaps, 171 is the result if somebody goes with the construct that there are 9 girls and 19 boys ...
Naveenan Ramachandran
4GMAT, Dadar(W) & Ghatkopar(W), Mumbai
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 1179
Joined: Sun Apr 11, 2010 9:07 pm
Location: Milpitas, CA
Thanked: 447 times
Followed by:88 members

by Rahul@gurome » Mon Dec 20, 2010 8:05 am
goyalsau wrote:In a chess competition involving some boys and girls of a school, every student had to play exactly one game with every other student. It was found that in 45 games both the players were girls, and in 190 games both were boys. The number of games in which one player was a boy and the other was a girl is

1. 200
2. 216
3. 235
4. 256
5. 171
Let number of girls = g and number of boys = b
Then gC2 = 45 => g(g - 1) = 90 => g = 10
and bC2 = 190 => b(b - 1) = 380 => b = 20

Number of games in which one player was a boy and the other was a girl = (Number of ways to select a girl out of 10)*(Number of ways to select a boy out of 20) = 10*20 = 200

The correct answer is A.
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
Top
User avatar
Legendary Member
Posts: 866
Joined: Mon Aug 02, 2010 6:46 pm
Location: Gwalior, India
Thanked: 31 times

by goyalsau » Mon Dec 20, 2010 8:15 am
4GMAT_Mumbai wrote:Hi,

If both players were girls in 45 games; then there are 10 girls

If both players were boys in 190 games; then there are 20 boys.

Hence, there are 200 games involving a boy and a girl.

PS ... Perhaps, 171 is the result if somebody goes with the construct that there are 9 girls and 19 boys ...
Thanks Buddy, I forgot to add 1

Thanks...
Saurabh Goyal
[email protected]
-------------------------


EveryBody Wants to Win But Nobody wants to prepare for Win.
Top
Post new topic Post Reply
• Page 1 of 1