Thinking Mathematically (6th Edition)

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

Chapter 11 - Counting Methods and Probability Theory - Chapter Summary, Review, and Test - Review Exercises - Page 758: 20

Answer

$ 210$

Work Step by Step

First we ask, does order of selection matter? Being selected first or fourth does not matter, you are a commissioner either way. Order does not matter, we use combinations. Combinations Formula: The number of combinations possible if $r$ items are taken from $n$ items is ${}_{n}C_{r}=\displaystyle \frac{n!}{(n-r)!r!}$ r=4 candidates are taken from n=10 candidates. ${}_{10}C_{4}=\displaystyle \frac{10!}{(10-4)!4!}=\frac{10\times 9\times 8\times 7\times 6!}{6!\cdot 4!}$ ... reduce the fraction by 6! $ =\displaystyle \frac{10\times(9\times 8)\times 7 }{(4\times 3\times 2)\times 1}\qquad$... reduce the fraction $=10\times(3)\times 7 $ $=210$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.