Question

A civil patrol unit of 15 members includes 4 officers. In how many ways can 3 members be selected for a search and rescue mission such that at least 1 officer is included?

Answer 1

Explanation:

There are 4 ways to select an officer

multiply this by the number of ways to select 2 others from the 15

4 * 15 C 2 = 4 * 15!/(2!13!) = 420 ways to select