Statistics (12th Edition)

Published by Pearson
ISBN 10: 0321755936
ISBN 13: 978-0-32175-593-3

Chapter 3 - Probability - Exercises 3.1 - 3.34 - Learning the Mechanics - Page 120: 3.12b

Answer

$21$

Work Step by Step

Combinations Rule $$\binom{N}{n} = \dfrac{N!}{n! (N-n)!}$$ ${\displaystyle{\binom{7}{2}} = \dfrac{7!}{2! \, 5!} = \dfrac{7 \cdot 6 \cdot 5 \cdot 4 \cdot 3 \cdot 2 \cdot 1}{(2 \cdot 1)(5 \cdot 4 \cdot 3 \cdot 2 \cdot 1)}= \dfrac{7 \cdot 6}{2 \cdot 1}}$ ${\displaystyle{\binom{7}{2}} = \dfrac{7 \cdot 6}{2 \cdot 1} = \dfrac{42}{2} = \boxed{21}}$
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.