Elementary Statistics (12th Edition)

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

Chapter 5 - Discrete Probability Distributions - 5-5 Poisson Probability Distributions - Basic Skills and Concepts - Page 233: 8


0.06, not unlikely.

Work Step by Step

By using the formula: $P(12)=\frac{\mu^k\cdot e^{-\mu}}{x!}=\frac{8.5^{12}\cdot e^{-8.5}}{12!}=0.06.$ If a value is unusual, then it is more than two standard deviations far from the mean. $Minimum \ usual \ value=mean-2\cdot(standard \ deviation)=8.5-2\cdot\sqrt{8.5}=2.67$ $Maximum \ usual \ value=mean+2\cdot(standard \ deviation)=8.5+2\cdot\sqrt{8.5}=14.33$. 12 is between the two bounds therefore it is not unlikely.
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.