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#1 2008-11-06 05:39:34
- Danbee
- Member
- Registered: 2008-08-28
- Posts: 21
Permutations and combinations
The student government at central high school consists of 4 seniors, 3 juniors, 3 sophomores, and 2 freshmen. How many different nine-student committees can be formed that include, at most, one freshman?
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#2 2008-11-06 06:06:43
- All_Is_Number
- Member
- Registered: 2006-07-10
- Posts: 258
Re: Permutations and combinations
nCr(2,1)*nCr(10,8) + nCr(10,9)
You can shear a sheep many times but skin him only once.
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#3 2008-11-06 06:21:57
- Ricky
- Moderator
- Registered: 2005-12-04
- Posts: 3,791
Re: Permutations and combinations
My guess is that each junior is considered to be the same. If that's right, then this is a balls in bin problem.
"In the real world, this would be a problem. But in mathematics, we can just define a place where this problem doesn't exist. So we'll go ahead and do that now..."
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