In a study of heart surgery, one issue was the effect of drugs called beta blockers on the pulse rate of patients during surgery. The available subjects were randomly assigned into two groups. One group received a beta blocker; the other group received a placebo. The pulse rate of each patient at a critical point during the operation was recorded. Here are the data in summary form: 

a. The distribution of pulse rate in each group is not Normal. The use of two-sample t procedures is still justified. Why?

b. Construct and interpret a 99% confidence interval for the difference in mean pulse rates for patients like these who receive a beta blocker or a placebo.

c. Interpret the 99% confidence level in the context of this study.

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305 = 0.200 = 20.0% х 1526 Group Beta blocker 30 65.2 7.8 Placebo 30 70.3 8.3