Question

Four out of 9 performers will be chosen to stand in a row on stage. How many ways can the 4 performers stand in a row

Answer 1

126

Explanation:

Answer 2

The number of ways to choose k items out of n items is:

`(n!)/(n!(n-k)!)`

Plug in n as 9 and k as 4, and that's the answer:

`(9!)/(4!(9-4)!) = 9*8*7*6*5/5/4/3/2 = 126`