a. The sample mean and standard deviation from a random sample of 10 observations from a normal population were computed as x̄ = 23 and s = 9. Calculate the value of the test statistic 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 of increasing the sample size.