Question

Five students were late to class and only three vacant seats were available. In how many ways can the seats be occupied?

Answer 1

You are filling 3 seats with 5 students.
What have you studied about permutations?
In how many ways can you fill the first empty seat?
Now that there are only 4 of the late students standing, in how many ways can you fill the 2nd empty seat?
etc.