Question # 1

A high school counselor wanted to know if tenth-graders at her high school tend to have more free time than the twelfth-graders. She took random samples of 27 tenth-graders and 18 twelfth-graders. Each student was asked to record the amount of free time he or she had in a typical week. The mean for the tenth graders was found to be 72 hours of free time per month with a standard deviation of 2.2 hours. For the twelfth graders, the mean was 68 hours of free time per month with a standard deviation of 2.5 hours. Assume that the two populations are normally distributed with equal but unknown population standard deviations.