Chapter 0.5, Problem 16E

To determine

whether each situation involves a permutation or a combination and then to find the number of possibilities.

Answer to Problem 16E

The numbers of possibilities are 45possibilities .

Explanation of Solution

Given information :

It is given that to choose 2 CDs to buy from 10 that are on sale.

In the given event, arrangement does not matter so it is combination.

The number of possibilities is given by,

  $\begin{array}{c}C{}_2=\frac{10!}{2!\times 8!}\\ =\frac{10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2}{2\times 1\times 8\times 7\times 6\times 5\times 4\times 3\times 2}possibilities\\ =\frac{10\times 9}{2\times 1}possibilities\\ =45possibilities\end{array}$

So, the numbers of possibilities are 45possibilities .