In a recent study of the effectiveness of streptokinase in the treatment of patients who have been hospitalized after myocardial infarction, 9 of 199 males receiving streptokinase and 13 of 97 males in the control group died within 12 months.

a) Find a 95% confidence interval for the difference in the proportion of deaths between the streptokinase and the control group.

b) At a level of α of 1%, can we conclude that the proportion of deaths in the streptokinase group is smaller than that of the control group? What is the p-value? Explain the meaning of this p-value in your own words.

c) Can you conclude that the proportion of deaths in the streptokinase group is less than 5%. Use α = 2%. What is the p-value?

d) For the streptokinase group, if you wish to estimate the proportion of deaths to within 2% of the true value, with a level of confidence of 90%, how many samples would you have to select?