Consider the dissolved oxygen concentration at TVA dams first presented in Exercise 8-81.
(a) Test the hypotheses H0: μ = 4 versus H1 μ  4 Use a = 0.01.
(b) What is the P-value of the test statistic computed in part (a)?
(c) Compute the power of the test if the true mean dissolved oxygen concentration is as low as 3.
(d) What sample size would be required to detect a true mean dissolved oxygen concentration as low as 2.5 if we wanted the power of the test to be at least 0.9?