Question

In how many ways can you select five people from a group of nine if the order of selection is important?

Answer 1

If the order of the selection is important we will apply the Arrangements formula $A_{n} ^{k}= \frac{n!}{(n-k)!}$.
In our case we will have $A_{9}^{5}= \frac{9!}{4!} =5*6*7*8*9=15120.$