Question

A relay team of 4 swimmers is to be formed from a swim team with 20 member. How many different relay teams are possible?

Answer 1

When order does not matter you use what is called n choose k formula

n!/(k!(n-k)!) where n is the number of things to choose from and k is the number of choices made, in this case:

20!/(4!(20-4)!)=4845