Consider the following two groups of women: Group 1 consists of women who spend less than $500 annually on clothes; Group 2 comprises women who spend more than $1000 annually on clothes. Let py and P2 equal the proportions of women in these two groups respectively, who believe that clothes are too expensive. If 1009 out of a random sample of 1230 women from group 1 and 207 out of a random sample of 340 from group believe that clothes are too expensive.
(a) Give a point estimate of PL - P2.
(b) Find an approximate 95% confidence interval for PI - P2.