Construct the 95% two-sided confidence interval
and one-sided intervals of the population mean with the sample: 15, 30, 45, 10,
20, 8, 6, 7, 21, 25, 10, 20, 20, 30, 40.

Our sample mean is 20.467 . Our sample standard deviation is 11.898. For the two-sided interval, we want +/- 1.96 standard deviations from the mean. That is, we want (-2.853 ,43.787). For a one-sided interval, we want z score 1.645. That is, we get (-infinity, 40.039) and (0.895, infinity)