11.50 The article referenced in the previous exercise also reported that 5.7% of high school graduates were unemployed in 2008 and 9.7% of high school graduates were unemployed in 2009. Suppose that the reported percentages were based on independently selected representative samples of 400 high school graduates in each of these two years.

a. Construct and interpret a 99% confidence interval for the difference in the proportion of high school graduates who were unemployed in these two years.

b. Is the confidence interval from Part

(a) wider or narrower than the confidence interval computed in the previous exercise? What are two reasons why it is wider or narrower?