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 After 8.6 6.2 2.9 10.8 11.0 12.6 9.7 2.7 7.7 8.7 8.5 6.6 8.0 3.9 5.7 2.3 Construct a 95% confidence interval for the mean of the "before-after" differences. < Hd (Round to two decimal places as needed.)