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 in 2004 reveals the following family dental expenses (in dollars): 115, 370, 250, 93, 540, 225, 177, 425, 318, 182, 275, and 228..

The sample mean is _____

. Construct a 95% confidence interval estimate of the mean family dental expenses for all employees of this corporation. The upper boundary/limit is

______

and the lower boundary/limit is

_____

. (Please keep two decimal points.)