Question

Find the number of different ways 4 books can be placed on a shelf if there are 8 books to choose from?

Answer 1

1680

Explanation:

This is a permutation question so we will use the permutation formula.

P(n, r) = n!/(n-r)!

n represents what we are given

r represents what we have to choose

so it becomes

P (8,4) = 8!/(8-4)!

P = 8!/4!

P = 1680

there are 1680 different ways that 4 books can be placed on a shelf when given 8 books to choose from