8.108 University Costs A university administra- tor wishes to estimate the average cost of the first year at a particular university correct to within $500, with a probability of 0.95. If a random sample of first-year students is to be selected and each asked to keep financial data, how many must be included in the sample? Assume that the dean knows only that the range of expenditures will vary from approximately $4800 to $13,000.