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 6.0 3.7 12.3 7.1 11.8 9.6 6.2 3.8 After 6.7 2.4 7.9 8.7 8.2 6.1 3.8 2.1 Construct a 95% confidence interval for the mean of the "before - after" differences.