Question

How many ways can an adviser choose 3 students from a class of 10?

Answer 1

720

Explanation:

At first, there are 10 students available, so there are 10 possibilities.

As the student cannot be chosen again, there are now 9 students available, but each of the 9 possibilities is possible for each 10 earlier, `9*10=90`.

Now there are only 8 to choose from, 8 possibilities for 9 different posibilities before that, for 10 possibilities before that: `8*9*10=720`.