Let the following sample of 8 observations be drawn from a normal population with unknown mean and

Question:

Let the following sample of 8 observations be drawn from a normal population with unknown mean and standard deviation: 22, 18, 14, 25, 17, 28, 15, 21.
a. Calculate the sample mean and the sample standard deviation.
b. Construct the 80% confidence interval for the population mean.
c. Construct the 90% confidence interval for the population mean.
d. What happens to the margin of error as the confidence level increases from 80% to 90%?