# Question: An automobile dealer has an inventory of 328 used cars

An automobile dealer has an inventory of 328 used cars. The mean mileage of these vehicles is to be estimated. Previous experience suggests that the population standard deviation is likely to be about 12,000 miles. If a 90% confidence interval for the population mean is to extend 2,000 miles on each side of the sample mean, how large of a sample is required if simple random sampling is employed?

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