A random sample of 15 students was selected from a population size of 100 (normal) in a certain dormitory. The mean is weekly expenditures of the sample students is ₱400 with ₱17.50 standard...

A random sample of 15 students was selected from a population size of 100 (normal) in a certain dormitory. The mean is weekly expenditures of the sample students is ₱400 with ₱17.50 standard deviations. Construct a 95% confidence interval for the average amount of expenditure of the resident in the dormitory.