Question

Choosing seats If $4$people enter a bus having$9$vacant seats, in how many ways can they be seated?

Short answer

The answer is$15,120.$

Step-by-step solution

Step 1. Given information.

Number of people are $4$and number of seats are $9.$

Step 2. Calculation.

$$\begin{gathered} P\left(9,4\right)=\frac{9!}{4!} \\ =\frac{9\times 8\times 7\times 6\times 5\times 4!}{4!} \\ =9\times 8\times 7\times 6\times 5 \\ =15,120 \end{gathered}$$