A student has time to see four films on his vacation. If he is selecting the movies from a total of nine choices, how many ways can he choose the films?

Question

Quizplus · Accepted Answer

The correct way to calculate the number of ways to choose 4 films out of 9 is to use the combination formula, which is $\frac{n!}{r!(n-r)!}$, where $n$ is the total number of items (9 films) and $r$ is the number of items to choose (4 films). This simplifies to $\frac{9!}{4!(9-4)!}$, which further simplifies to $\frac{9 \cdot 8 \cdot 7 \cdot 6}{4 \cdot 3 \cdot 2 \cdot 1}$, matching option D.

A Student Has Time to See Four Films on His 9⋅49 \cdot 49⋅4

A Student Has Time to See Four Films on His $9 \cdot 4$