A study was conducted to measure the effectiveness of hypnotism in reducing pain. The measurements are centimeters on a pain scale before and after hypnosis. Assume that the paired sample data are simple random samples and that the differences have a distribution that is approximately normal. Construct a 95% confidence interval for the mean of the "before - after" differences. Does hypnotism appear to be effective in reducing pain? Before 9.0 5.1 6.5 8.7 9.9 6.4 1.9 2.0 After 6.8 2.3 7.3 8.9 8.7 6.8 3.5 2.9 . . . Construct a 95% confidence interval for the mean of the "before - after" differences.