Please help with the following question

According to the Journal of the American Medical Association, resident doctors worked an average of 59.3 hours per week at hospitals from 2006 to 2008. The accreditation council for graduate Medical Education which certifies residency programs in hospitals, has developed a plan to reduce the long hours resident doctors work. To investigate the plan's effectiveness, a random sample of the hours worked per week by 20 resident doctors was recently selected. They are as follows: 53 57 52 65 70 51 55 61 49 61 45 59 39 52 50 55 48 56 46 51 a. Create a 95% confidence interval for the number of hours worked by resident doctors based upon this sample. b. Test the hypothesis that the new plan has had no effect on the number of hours worked by resident doctors at the alpha = .05 level of significance