3 Freshmen
5 Sophomores
7 Juniors
9 Seniors
To form a committe with 8 members
At most 4 Sophomores
Please show solutions thanks!
Permutation question - Combination
This topic has expert replies
GMAT/MBA Expert
- Anurag@Gurome
- GMAT Instructor
- Posts: 3835
- Joined: Fri Apr 02, 2010 10:00 pm
- Location: Milpitas, CA
- Thanked: 1854 times
- Followed by:523 members
- GMAT Score:770
We have to select 8 members from (3 + 5 + 7 + 9) = 24 candidatesPursuit wrote:3 Freshmen
5 Sophomores
7 Juniors
9 Seniors
To form a committe with 8 members
At most 4 Sophomores
Hence, total number of possible selections = 24C8
But some of these selections will have all the 5 sophomores in them which is not permitted by the condition "at most 4 Sophomores". We need to discard those selections.
Number of such selections = (number of ways to select all the 5 sophomores)*(number of ways to select (8 - 5) = 3 members from (24 - 5) = 19 candidates) = 1*19C3 = 19C3
Hence, number os valid selections = 24C8 - 19C3
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)
Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)
Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/