The personnel department of a large corporation wants to estimate the family dental expenses of its employees to determine the feasibility of providing a dental insurance plan. A random sample of 12 employees reveals the following family dental expenses (in dollars).

See Attached Excel for Data. 115 370 250 593 540 225 177 425 318 182 275 228

dental expense data.xlsx

Construct a 90% confidence interval estimate for the mean of family dental expenses for all employees of this corporation.