Statistics: Informed Decisions Using Data (4th Edition)

Published by Pearson
ISBN 10: 0321757270
ISBN 13: 978-0-32175-727-2

Chapter 5 - Section 5.5 - Assess Your Understanding - Applying the Concepts - Page 306: 46

Answer

In $90$ ways.

Work Step by Step

The order in which the horses finish the race matters and one horse can not finish in two different positions. Permutation of 10 distinct horses taken 2 at a time: $_2P_{10}=\frac{10!}{(10-2)!}=\frac{10!}{8!}$ But, $10!=10\times9\times(8\times7\times6\times5\times4\times3\times2\times1)=10\times9\times8!$ $_2P_{10}=\frac{10\times9\times8!}{8!}=10\times9=90$
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