i've attached the question below, please explain what formulas you use and also we are not allowed to use excel.

A physician employed by a large corporation believes that employees have gained body fat as a result of working from home during the pandemic. In 1970, the corporation measured the percentage of body fat for every employee. The scores were normally distributed with a mean of 22% body-fat. The physician measures the body fat percentage in a random sample of 12 workers employed by the corporation. The fat percentages found were as follows: 23, 39, 28, 31, 32, 24, 15, 22,18,25,16,27. a) What is the mean and standard deviation of the sample [3 marks)? b) Use a one-tailed test with cc = .05 to determine whether the physician's beliefs are accurate [9 marks]. c) Report and interpret the effect size using We! [3 marks). d) Report and interpret the 99% condence interval [4 marks)