Worker Fatigue. The null and alternative hypotheses obtained in Exercise 9.20 on page 375 are, respectively, H0: μ = 72 bpm Ha: μ > 72 bpm, where μ is the mean post-work heart rate of all casting workers.

i. σ = 11.2 ii. α = 0.05 iii. n = 29 iv. μa = 73, 74, 75, 76, 77, 78, 79, 80