A recent study examined the association between high blood pressure and increased risk of death from cardiovascular disease. There were 2676 men with low blood pressure and 3338 men with high blood pressure. In the low-blood pressure group, 21 men died from cardiovascular
disease; in the high-blood-pressure group, 55 died.
a. Compute the 95% confidence interval for the difference in proportions.
b. Do the study data confirm that death rates are higher among men with high blood pressure? State hypotheses, carry out a significance test,
and give your conclusions.