Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 11 - Counting Methods and Probability Theory - 11.3 Combinations - Exercise Set 11.3 - Page 708: 72


Does not make sense.

Work Step by Step

"...ranking from ..." implies that the order of selected politicians matters. It makes a difference whether the politician was selected first or fifth. Permutations should be used, not combinations. The formula for ${}_{n}P_{r}$ should be used.
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