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Senior Manager
Joined: 20 Dec 2004
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A Committee of 6 is chosen from 8 men and 5 women, so as to [#permalink]
25 Dec 2007, 12:56
Question Stats:
0% (00:00) correct
0% (00:00) wrong based on 0 sessions
A Committee of 6 is chosen from 8 men and 5 women, so as to contain at least 2 men and 3 women. How many different committees could be formed if two of the men refuse to serve together?
A- 3510
B- 2620
C- 1404
D- 700
E- 635
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Director
Joined: 23 Sep 2007
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My guess would be E, by POE.
the committee can be 2 men, 4 women or 3 men and 3 women.
2 men out of 8 = C(8,2) = 28
4 women out of 5 = C(5,4) = 5
28 x 5 = 140
3 men out of 8 = C(8,3) = 56
3 women out of 5 = C(5,3) = 10
56 x 10 = 560
Add the possible combos
560 + 140 = 700
But we need to eliminate the combos that the 2 men who refused to server together.
Therefore, less than 700
of the 28 combos of 2 men, 1 combo contains the 2 men who don't serve together ---> 1 x 5 (4 women combo) = 5
of the 56 combos of 3 men, if 2 men don't serve together, then C(6,1) = 6
6 x 10 (3 women combo) = 60
60 + 5 = 65
700-65=635
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