The personnel department of a large corporation wants toestimate the family dental expenses of its employees to determinethe feasibility of providing a dental insurance plan. A randomsample of 12 employees in 2004 reveals the following dentalexpenses (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 forall employees of this corporation. The upper boundary/limit is_________ and the lower boundary/limit is ________. (keep twodecimal points).
