SOLUTION: Assume that the set S has 13 elements. How many subsets of S have at most 3 elements?

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Question 823136: Assume that the set S has 13 elements.
How many subsets of S have at most 3 elements?
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
The number of subsets which have 0 elements is C(13,0) = 1, the empty set.
The number of subsets which have exactly 1 element is C(13,1) = 13.
The number of subsets which have exactly 2 elements is C(13,2) = 78.
The number of subsets which have exactly 3 elements is C(13,1) = 286.

Total: 1+13+78+286 = 378 subsets have at most 3 elements.

Edwin