10.31 Time spent on social networks As part of a class exercise, an instructor at a major university asks her students how many hours per week they spend on social networks. She wants to investigate whether time spent on social networks differs for male and female students at this university. The results for those age 21 or under were:

Males: 5, 7, 9, 10, 12, 12, 12, 13, 13, 15, 15, 20 Females: 5, 7, 7, 8, 10, 10, 11, 12, 12, 14, 14, 14, 16, 18, 20, 20, 20, 22, 23, 25, 40

a. Using software or a calculator, find the sample mean and standard deviation for each group. Interpret.

b. Find the standard error for the difference between the sample means.

c. Find and interpret a 90% confidence interval comparing the population means.