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):
10–19
20–39
40–59
60–69
29
24
37
28
33
27
25
26
22
34
31
36
39
21
35
20
30
32
Total 309
275
295
282
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 = .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 .95?
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