## Thinking Mathematically (6th Edition)

Published by Pearson

# Chapter 11 - Counting Methods and Probability Theory - 11.3 Combinations - Exercise Set 11.3 - Page 707: 17

1

#### Work Step by Step

The number of possible combinations if r items are taken from n items is nCr = $\frac{n!}{r!(n-r)!}$ 5C0 = $\frac{5!}{0!(5 -0)!}$ =$\frac{5!}{0!5!}$ 0!=1, so the expression reduces to 1.

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