According to a national representative survey done by Consumer Reports, you should always try to negotiate for a better deal when shopping or paying for services. Tips include researching prices at other stores and on the Internet, timing your visit late in the month when sales-people are trying to meet quotas, and talking to a manager rather than a salesperson. Suppose that random samples of 200 men and 200 women are taken, and that the men were more likely than the women to say they "always or often" bargained (30% compared with 25%).
a. Construct a 95% confidence interval for the difference in the proportion of men and women who say they "always or often" negotiate for a better deal.
b. Do the data indicate that there is a difference in the proportion of men and women who say they "always or often" negotiate for a better deal? Explain.