Coaching and SAT scores, continued. What we really want to know is whether coached students improve more than uncoached students, and whether any advantage is large enough to be worth paying for. Use the information in the previous exercise to answer these questions: (a) Is there good evidence that coached students gained more on the average than uncoached students? (b) How much more do coached students gain on the average? Give a 99% confidence interval. (c) Based on your work, what is your opinion: do you think coaching courses are worth paying for?