A study was conducted to estimate hospital costs for accident victims who wore seat belts. 20 randomly selected cases have a distribution that appears to be bell-shaped with a mean of $9004 and a standard deviation of $5629.
a) Construct the 99% confidence interval for the mean of all such costs
b) If you are a manager for an insurance company that provides lower rates for drivers who ear seat belts, and you want a conservative estimate for a worst case scenario, what amount should you use as the possible hospital cost for an accident victim who wears seat belts?