Question

The following data give the prices of seven textbooks randomly selected from a university bookstore.

Answer 1

Answer:

a) Mean = $121

Sum of deviations = $0

b) Standard deviation = 41.19

Variance = 1696.67

Range = $120

Step-by-step explanation:

We are given the following data:

$91 , $176 , $108 , $115 , $56 , $157 , $144

a) Mean and sum of deviations

$Mean = \displaystyle\frac{\text{Sum of all observations}}{\text{Total number of observation}}$

$Mean =\displaystyle\frac{847}{7} = 121$

Sum of deviations =

-30 + 55 - 13 - 6 - 65 + 36 + 23 = 0

The sum of deviations is zero dollars.

b) range, variance, and standard deviation

$\text{Standard Deviation} = \sqrt{\displaystyle\frac{\sum (x_i -\bar{x})^2}{n-1}}$  

where $x_i$ are data points, $\bar{x}$ is the mean and n is the number of observations.

Sum of square of differences =

900 + 3025 + 169 + 36 + 4225 + 1296 + 529 = 10180

$\sigma = \sqrt{\dfrac{10180}{6}} = 41.19\\\\\sigma^2 = 1696.67$

Sorted data: 56, 91, 108, 115, 144, 157, 176

Range = Maximum - Minimum

Range = 176 - 56 = 120