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Combinatorics #3

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Combinatorics #3

by papgust » Sun Oct 18, 2009 5:13 am
There are ten subjects in the school day at St.Vincent's High School, but the sixth standard students have only 5 periods in a day. In how many ways can we form a time-table for the day for the sixth standard students?

A. 5^10
B. 10^5
C. 252
D. 30,240

Solution and explanation pls?
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by NikolayZ » Sun Oct 18, 2009 8:46 am
Hello =)

So, here, we have a permutation problem, since order of lessons matters. (history-math, is different from math-history)
so, we have to choose 5 lessons from 10.

10!/5! = 30240.

Again, if i didn't mix up permutation and combination =)
What is the OA plz ?
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by papgust » Sun Oct 18, 2009 10:59 pm
you are right again! OA is 30,240
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