Are parents of girls more inclined to buy them a car when they leave for college than parents of boys? Simple random samples of 40 girls and 45 boys are taken from a large university on the West Coast. When interviewed, 20 girls and 21 boys in the sample responded that their parents bought them a car. What is a 95% confidence interval for the difference in population proportions of girls and boys whose parents bought a car for them when they left for college? Use girls as Group 1 and boys as Group 2