Elementary Statistics (12th Edition)

Published by Pearson
ISBN 10: 0321836960
ISBN 13: 978-0-32183-696-0

Chapter 5 - Discrete Probability Distributions - 5-4 Parameters for Binomial Distributions - Basic Skills and Concepts - Page 226: 5


Mean:12. Standard deviation:3.1. Minimum usual value:5.8, maximum usual value:18.2.

Work Step by Step

Mean=$n\cdot p=60 \cdot 0.2=12$. Standard deviation: $\sqrt{n \cdot p \cdot (1-p)}=\sqrt{60 \cdot 0.2 \cdot 0.8}=3.1.$ If a value is unusual, then it is more than two standard deviations far from the mean. $Minimum \ usual \ value=mean-2\cdot(standard \ deviation)=12-2\cdot3.1=5.8$ $Maximum \ usual \ value=mean+2\cdot(standard \ deviation)=12+2\cdot3.1=18.2$.
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