Assume that an insurance survey is based on 1,000 randomly selected U.S. households in a particular income class and finds that 640 of these households bought life insurance last year.
a. If p denotes the proportion of all U.S. households in the income class that bought life insurance last year, set up the null and alternative hypotheses needed to attempt to justify the claim that more than 60 percent of U.S. households in the income class bought life insurance last year.

b. Test the hypotheses you set up in part a by setting a = .10, .05, .01, and .001. How much evidence is there that more than 60 percent of U.S. households in the income class bought life insurance last year?