Essentials of Statistics (5th Edition)

Published by Pearson
ISBN 10: 0-32192-459-2
ISBN 13: 978-0-32192-459-9

Chapter 7 - Estimates and Sample Sizes - 7-3 Estimating a Population Mean - Page 354: 34

Answer

$\mu$ is between 134.252 and 210.698.

Work Step by Step

The mean can be counted by summing all the data and dividing it by the number of data: $\frac{1+0+...+173}{40}=172.475.$ Standard deviation=$\sqrt{\frac{\sum (x-\mu)^2}{n-1}}=\sqrt{\frac{(1-172.475)^2+...+(173-172.475)^2}{39}}=119.4983.$ $\alpha=1-0.95=0.05.$ $\sigma$ is unknown, hence we use the t-distribution with $df=sample \ size-1=40-1=39$ in the table. $t_{\alpha/2}=t_{0.025}=2.023.$ Margin of error:$z_{\alpha/2}\cdot\frac{s}{\sqrt {n}}=2.023\cdot\frac{119.4983}{\sqrt{40}}=38.223.$ Hence the confidence interval:$\mu$ is between 172.475-38.223=134.252 and 172.475+38.223=210.698.
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.