Posted by Ashley on Friday, February 28, 2014 at 4:43pm.
There are 7 different books on a shelf. How many selections of more than 4 books can be made?

Math 302  Steve, Friday, February 28, 2014 at 4:48pm
7C4 + 7C5 + 7C6 + 7C7 = 64
since
n
∑ nCk = 2^n
k=0