Subjects with preexisting cardiovascular symptoms who were receiving sibutramine, an appetite suppressant, were found to be at increased risk of cardiovascular events while taking the drug. The study included9844overweight or obese subjects with preexisting cardiovascular disease and/or type2diabetes. The subjects were randomly assigned to sibutramine ( 4899subjects) or a placebo ( 4945subjects) in a doubleblind fashion. The primary outcome measure was the occurrence of any of the following events: nonfatal myocardial infarction or stroke, resuscitation after cardiac arrest, or cardiovascular death. The primary outcome was observed in568subjects in the sibutramine group and505subjects in the placebo group.

Do the data give good reason to think that there is a difference between the proportions of treatment and placebo subjects who experienced the primary outcome?

(Note that sibutramine has not been available in the United States since the end of 2010 due to its manufacturer's concerns over increased risk of heart attack or stroke, although at the present time, it can still be purchased in other countries.)

State hypotheses and then find the test statistic. Give your answer to two decimal places.

=

Use either software or the bottom row of Table C for the-value.Give your answer to four decimal places.

-value:

2.Is drinking tea good for your health? Researchers in China studied a sample of100,902adults and classified them as habitual tea drinkers ( 3or more cups per week) and never/nonhabitual tea drinkers (less than3cups per week). These subjects were followed for several years, and the number of subjects who had strokes was recorded. Of the69,017subjects who were never/nonhabitual tea drinkers,2949had strokes. Of the31,885habitual tea drinkers,854had strokes.

Find the test statistic. Give your answer to two decimal places.

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Give a95%confidence interval for the difference between the proportions of habitual tea drinkers and never/nonhabitual tea drinkers who had strokes. Give your answer as an interval in the form (lower bound, upper bound). Give your bounds to four decimal places.

95%confidence interval: