Question

There are 20 players on a soccer team. From them, a captain and an alternate captain have to be chosen. How many possibilities are there?

Answer 1

190 possibilities.

Explanation:

The problem is called 20 choose 2, given by the formula for combinations

C(20,2) = 20! / (2! (20-2)!) = 190

alternatively, we can reason it this way:

there are 20 choices to choose a captain and 19 choices for an alternate captain for a total of 380 ways.

However, there are 20 choices to choose an alternate captain and 19 choices for a captain for a total of 380 ways.

Since we are essentially double counting every choice of the posts, we need to divide 380 by 2 to get 190 ways.