Question

In the opening for mathematics fair, 3 students out of the 20 participants will be chosen to sing the national anthem, to lead the invocation, and to introduce the guest speaker. How many ways can the 3 students be chosen?

Answer 1

Given that there are 20 participants and only 3 students to choose to. The number of ways the 3 students can be chosen is

`\begin{gathered} _(20)C_3=(20!)/(3!(20-3)!) \\ _(20)C_3=(20!)/(3!\cdot17!) \\ _(20)C_3=1140 \end{gathered}`

Therefore, there are 1140 ways the 3 students can be chosen.