Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 10 - Review Exercises - Page 1126: 82


The number of ways five planes can be lined up for departure is: 120.

Work Step by Step

We know that the order in which the five planes can line up for departure on a runway matters. Thus, we use permutations. Here, $ n=5,r=5$. $\begin{align} & _{5}{{P}_{5}}=\frac{5!}{\left( 5-5 \right)!} \\ & =\frac{5!}{0!} \\ & =\frac{5\times 4\times 3\times 4\times 1!}{1} \\ & =120 \end{align}$
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