In each part, assume that the population standard deviation is known. Decide whether use of the z-interval procedure to obtain a confidence interval for the population mean is reasonable.
Explain your answers.
a. The variable under consideration is very close to being normally distributed, and the sample size is 10.
b. The variable under consideration is very close to being normally distributed, and the sample size is 75.
c. The sample data contain outliers, and the sample size is 20.