Eliminate possibilities Please write answer step by step A p

Eliminate possibilities

*************Please write answer step by step************

A pilot and copilot are chosen from a group of five pilots. How many different crews are possible?

Solution

We assume that a pilot in a crew cannot be a co-pilot in another crew and also vice-versa. There are 5 different choices for the pilot. Also, once a pilot is chosen, there are 4 remaining possible choices for the copilot. Then, there are 5*4 = 20 possible different sets of crews. The answer is 20.