Chapter 9.3, Problem 103E

To determine

To find: The conditions that are not satisfied to perform a paired t -test.

Answer to Problem 103E

Randomization condition is not fulfilled.

Explanation of Solution

Given:

The dot plot and output are:

  

Concept used:

Following are the main requirements for the paired t- test:

1. The samples taken from the population are simple random samples.
2. The size of the sample must be at least 30.
3. Population must be at least 10% greater than the sample size.

In this case,

1. Data is gathered only on Friday and it is not possible that everyone goes out for the shopping on Friday. Thus, the sample is not random.
2. The sample size is 45 which is above 30. Thus, normality condition is fulfilled.
3. Sample size of 45 is lower than the 10% of the size of the population.

Thus, the correct option is (a).