Worker Fatigue. A study by M. Chen et al. titled “Heat Stress Evaluation and Worker Fatigue in a Steel Plant” (American Industrial Hygiene Association, Vol. 64, pp. 352–359) assessed fatigue in steelplant workers due to heat stress. Among other things, the researchers monitored the heart rates of a random sample of 29 casting workers.

A hypothesis test is to be conducted to decide whether the mean postwork heart rate of casting workers exceeds the normal resting heart rate of 72 beats per minute (bpm).