A Washington Post Poll (March 18, 2013) and a Pew Poll (March 17, 2013) both claimed to ask a random sample of adults in the United States whether they supported or opposed gay marriage. In the Washington Post Poll, 581 supported and 360 opposed gay marriage. In the Pew Poll, 735 supported and 660 opposed gay marriage.

a. Find the percentages supporting gay marriage in these two polls and compare them.

b. Test the hypothesis that the population proportions are not equal at the 0.05 significance level.

c. Using methods learned in Chapter 7, find a 95% confidence interval for the difference between the two percentages, and interpret it. Does it capture 0? What does that show?