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 7.2 8.9 12.6 10.8 9.2 4.6 1.9 After 6.7 2.9 7.5 8.1 8.9 6.5 3.4 2.4 Construct a 95% confidence interval for the mean of the "before - after" differences.