An insurance company is thinking about offering discounts on its life insurance policies to nonsmokers. As part of its analysis, the company randomly selects 200 men who are 60 years old and asks them whether they smoke at least one pack of cigarettes per day and if they have ever suffered from heart disease. (2 = Suffer from heart disease, 1 = Do not suffer from heart disease).

a. Can the company conclude at the 10% significance level that smokers have a higher incidence of heart disease than nonsmokers?

b. Estimate with 90% confidence the difference in the proportions of men suffering from heart disease between smokers and nonsmokers.