Question

At the airport, ten people are waiting on standby. Two seats become available, one first class and one coach. How many ways are there to fill the two seats?

10
20
45
90

Answer 1

90

Explanation:

Answer 2

Last Option

Explanation:

We have 10 people and two seats. Then we must choose 2 people out of 10 to occupy the seats.

The seats are different so the order in which people feel is important.

This is a problem of permutations

For the first seat I must choose a person of between 10.

For the second seat I must choose a person from 9.

So, if we call m the number of ways in which you can assign the seats:

`m = 10*9\\\\m = 90`