1. Shopping. A survey of 430 randomly chosen adults finds that 47 of 222 men and 37 of 208 women had pur- chased books online.
a) Is there evidence that the sex of the person and whether they buy books online are associated?
b) If your conclusion in fact proves to be wrong, did you make a Type I or Type II error?
c) Give a 95% confidence interval for the difference in proportions of buying online for men and women.
2. Information technology. A recent report suggests that Chief Information Officers (CIO's) who report directly to Chief Financial Officers (CFO's) rather than Chief Executive Officers (CEO's) are more likely to have IT agendas that deal with cost cutting and compliance (SearchCIO.com, March 14, 2006). In a random sample of 535 companies, it was found that CIO's reported directly to CFO's in 173 out of 335 service firms and in 95 out of 200 manufacturing companies.
a) Is there evidence that type of business (service versus manufacturing) and whether or not the CIO reports di- rectly to the CFO are associated?
b) If your conclusion proves to be wrong, did you make a Type I or Type II error?
c) Give a 95% confidence interval for the difference in proportions of companies in which the CIO reports di- rectly to the CFO between service and manufacturing firms.