Statistics (12th Edition)

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

Chapter 2 - Methods for Describing Sets of Data - Exercises 2.71 - 2.89 - Learning the Mechanics - Page 64: 2.78c

Answer

Range =$10$ Sample variance = $s^{2}=8$ Sample standard deviation = $s = 2.828$

Work Step by Step

Recall the shortcut formula for calculating the variance ($s^{2}$)$:$ $$s^{2}=\frac{\sum x_{i}^{2}-\frac{(\sum x_{i})^{2}}{n}}{n-1}$$ Create a table in which we compute $\displaystyle \sum x_{i}$ and $\displaystyle \sum x_{i}^{2}$: $$ \begin{array}{rrr} & x & x^{2}\\ \hline & 8 & 64\\ & -2 & 4\\ & 1 & 1\\ & 3 & 9\\ & 5 & 25\\ & 4 & 16\\ & 4 & 16\\ & 1 & 1\\ & 3 & 9\\ \hline\rm Sum & 27 & 145 \end{array}$$ Plug in the given values (there are $n=9$ data items): $$\begin{align*} s^{2}&= \displaystyle \frac{145-\frac{(27)^{2}}{9}}{9-1} & & \\ & =8 \\\\ s&= \sqrt{8} =2.828 \end{align*}$$ The range is the difference between the largest and smallest data item: $8-(-2)=10$
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.