Chapter 9.3, Problem 65E

To determine

To explain: The reason of not using the sample t -test in the provided scenario.

Explanation of Solution

Given:

The histogram is:

  

The output is:

  

Here, sample t -test cannot be used here because of the following reasons:

1. Sample has been selected through simple random technique.
2. Sample size is 20 which is less than 30. Thus, the assumption of normality is not fulfilled.
3. Distribution is skewed to the left and it could be confirmed from the histogram.

Thus, the sample t -test is not appropriate here.