Consider the dissolved oxygen concentration at TVA dams first presented in Exercise 8-105.

(a) Test the hypothesis H₀: μ = 4 versus H₁: μ ≠ 4. Use α = 0.01. Find the P-value.

(b) Check the normality assumption.

(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 you wanted the power of the test to be at least 0.9?

(e) Explain how the question in part (a) could be answered with a confidence interval.