12. A study was conducted to determine if the quality of life of the patients who had undergone a cosmetic surgery improve after undergoing the surgery. The quality of life was measured in score in which the higher the score, the better is the quality of life. A random sample of 26 patients was considered in the study. The table below shows the results of the study. Paired Samples Statistics Mean N Sid. Deviation Std. Error Mean Pair 1 Before 71.269 26 4.805 94227 After 81.485 26 7.647 1.4997 Paired Samples Test Paired Differences 95% Confidence Std. Interval of the Sid. Error Difference Sig. Mean Deviation Mean Lower Upper (2 tailed) Pair 1 Before - After X 8.404 Y -13.6097 -6.8211 -6.198 25 000 a) Find the values of X and Y. b) Let us be the difference in the average quality of life before and after undergoing the cosmetic surgery. State the 95% confidence interval for Jo. c) Is the quality of life of the patients improves after undergoing the cosmetic surgery