Chapter 0.5, Problem 19E

To determine

the ways can Jack select 9 books from the list to check out of the library.

Answer to Problem 19E

The numbers of possibilities are 220possibilities .

Explanation of Solution

Given information :

It is given that Jack has a reading list of 12 books.

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

The number of possibilities is given by,

  $\begin{array}{c}C{}_9=\frac{12!}{9!\times 3!}\\ =\frac{12\times 11\times 10\times 9\times 8\times 7\times 6\times 5\times 4\times 3\times 2}{9\times 8\times 7\times 6\times 5\times 4\times 3\times 2\times 3\times 2}possibilities\\ =\frac{2\times 11\times 10}{1}possibilities\\ =220possibilities\end{array}$

So, the numbers of possibilities are 220possibilities .