You work in the leasing office of GE capital and wish to predict the average mileage driven of your leased cars within a margin of error of 100 miles (you need this for your company's financial disclosures). Suppose your average customer drives 10,000 miles a year, and your guess for the standard deviation is about 500 miles. How big of a sample size do you need to generate a 95% confidence interval with a mean of 10,000 miles a year with a margin of error of 100 miles.