Chapter 12.2, Problem 23PPS

a)

To determine

To find : Is given sample a sample or population ?

Answer to Problem 23PPS

A sample

Explanation of Solution

Given Information :

The Iditarod is a $1150$ mile dog sled race across Alaska. A data of winning time, in days for recent years.

  $\text{{9, 9, 10, 9, 9, 8, 9, 9, 9, 9, 17, 15, 15, 14, 12, 16, 13, 13, 18, 12, 11, 11, 11, 11, 13, 11, 11, 11}}$

Calculation :

A sample.

Because it is for recent years, not all years.

b)

To determine

To find : Standard deviating of winning times.

Answer to Problem 23PPS

  $\text{2}\text{.65}$

Explanation of Solution

Given Information :

Data $\text{{9, 9, 10, 9, 9, 8, 9, 9, 9, 17, 15, 15, 14, 12, 16, 13, 13, 18, 12, 11, 11, 11, 11, 13, 11, 11, 11}}$

Formula Used:

  $\sigma =\sqrt{\frac{{\displaystyle \sum _{k=1}^w{(x_k-\mu )}^2}}{n}}$

Calculation :

  $\mu =\frac{\Sigma \text{data}}{\text{28}}=\frac{325}{28}=11.607$

  $\sigma =\sqrt{\frac{187.52}{28}}=\sqrt{7.054}=2.65$

Standard deviation, $\sigma =2.65$