Following are body mass index scores measured in 12 patients_Answer

The following are body mass index (BMI) scores measured in 12 patients who are free of diabetes and participating in a study of risk factors for obesity. Body mass index is measured as the ratio of weight in kilograms to height in meters squared.
A). Generate a 95% confidence interval estimate of the true BMI. 25 27 31 33 26 28 38 41 24 32 35 40.

B). How many subjects would be needed to ensure that a 95% confidence interval estimate of BMI had a margin of error not exceeding 2 units?