Exercise and heart rate. A student project measured the increase in the heart rates of fellow students when they stepped up and down for three minutes to the beat of a metronome. The explanatory variables are step height (Lo= 5.75 inches, Hi =11.5 inches) and metronome beat (Slow= 14 steps/minute, Med =21 steps/minute, Fast= 28 steps/minute). The subject's heart rate was measured for 20 seconds before and after stepping. The response variable is the increase in heart rate during exercise.12 The data file has resting and final heart rates as well as the increase in heart rate for this study. If the randomization worked well, there should be no significant differences among the 6 groups in mean resting heart rate (variable HRrest in the data file).

(a) How many pairwise comparisons are there among the means of 6 populations?

(b) Use Tukey's method to compare these means at the overall 10% significance level.