## Precalculus (10th Edition)

Published by Pearson

# Chapter 13 - Counting and Probability - 13.2 Permutations and Combinations - 13.2 Asses Your Understanding - Page 855: 22

#### Answer

$48620$

#### Work Step by Step

We know that $C(n,r)=\dfrac{n!}{(n-r)!r!}$. and $C(n,0)=1$. Hence $C(18,9)=\dfrac{18!}{(18-9)!\cdot9!}=\dfrac{18!}{9!\cdot9!}=48620$. (With the help of a calculator.)

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