In a Cohort Study of Smoking and Myocardial Infarction in City

Multiple Choice

In a cohort study of smoking and myocardial infarction in City A,the number of myocardial infarctions were 250 cases among 7,000 smokers and the number of myocardial infarctions were 150 cases among 20,000 nonsmokers.What is the attributable risk (risk difference) of smoking?

A) 2.8 per 1,000
B) 3.6 per 1,000
C) 7.5 per 1,000
D) 28.2 per 1,000
E) 35.7 per 1,000