Lila plays skee ball with her friends after school on Mondays and Wednesdays. Each time she rolls a ball, she can earn 10, 20, 30, 40, 50, or 100 points. Lila collected a random sample of ten rolls from each day that she played skee ball this week. The data is shown in the table. Monday Wednesday +/- 10 20 30 40 50 100 2 3 3 1 1 0 3 1 4 1 0 1 What is the difference in the mean number of points that Lila scored on Monday and Wednesday?