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 707: 16



Work Step by Step

The number of possible combinations if r items are taken from n items is nCr = $\frac{n!}{r!(n-r)!}$ 25C4 = $\frac{25!}{4!(25 -4)!}$ =$\frac{25!}{4!21!}$ =$\frac{25*24*23*22*21!}{4!21!}$ =$\frac{25*24*23*22}{4*3*2*1} \\= 12650$
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.