11.58 Heart Rate and Exercise An experiment was conducted to examine the effect of age on heart rate when a person is subjected to a specific amount of exercise. Ten male subjects were randomly selected from four age groups: 10-19, 20-39, 40-59, and 60-69. Each subject walked on a treadmill at a fixed grade for a period of 12 minutes, and the increase in heart rate, the difference before and after exercise, was recorded (in beats per minute):

Use an appropriate computer program to answer these questions:

a. Do the data provide sufficient evidence to indicate a difference in mean increase in heart rate among the four age groups? Test by using a = 0.05.

b. Find a 90% confidence interval for the difference in mean increase in heart rate between age groups 10-19 and 60-69.

c. Find a 90% confidence interval for the mean increase in heart rate for the age group 20-39.

d. Approximately how many people would you need in each group if you wanted to be able to estimate a group mean correct to within two beats per minute with probability equal to 0.95?

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10-19 20-39 40-59 60-69 29 24 37 28 33 27 25 29 26 33 22 34 27 31 33 36 39 21 28 21 35 28 26 20 33 24 30 25 29 34 34 24 36 21 27 33 22 32 33 32 Total 309 275 295 282