a. The sample mean and standard deviation from a random sample of 10 observations from a normal population were computed as and s  9.

Calculate the value of the test statistic (and for Excel users, the p-value) of the test required to determine whether there is enough evidence to infer at the 5% significance level that the population mean is greater than 20.

b. Repeat part

(a) with n  30.

c. Repeat part

(a) with n  50.

d. Describe the effect on the t-statistic (and for Excel users, the p-value) of increasing the sample size.