Astudy 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? in this​ example, μd is the mean value of the differences d for the population of all pairs of​ data, where each individual difference d is defined as the difference in the measurements in centimeters on a pain scale before and after hypnosis. what is the test statistic for this hypothesis test? (round to two decimal places as needed.)