Chapter 11.2, Problem 29S

To determine

To find: The number of possibilities.

Answer to Problem 29S

The number of possibilities are $120$ .

Explanation of Solution

The permutations are for lists (order matters) and combination are for groups (order doesn’t matter).

Since the order of the books is important, then the situation is a permutation.

The permutation formula is given as:

  $P\left(n,r\right)=\frac{n!}{\left(n-r\right)!}$

There are five unique books taken five at a time, so the number of possibilities are given as:

  $\begin{array}{c}P\left(5,5\right)=\frac{5!}{\left(5-5\right)!}\\ =\frac{5!}{0!}\\ =120\end{array}$

Therefore the number of possibilities are $120$ .