A sample of n = 25 respondents was selected for a study of their gas expenses for the last month. Individual records, {Xi : 1 i 25}, are assumed to be normal with unknown parameters (, ). Sample summaries were found as follows:

Mean = X = 187 and Standard Deviation = S = 40

1. At the significance level, = 0.05, is there enough evidence that the population mean = mu is

below 200?

2. At the significance level, = 0.01, is there enough evidence that the population mean = is above

170?

Show critical value and state the rejection rule in each case