mangement science the art of modeling w/ spreadshe
posted by melissa .
Five years ago, an automobile manufacturer started offering an extended warranty to buyers of its sportutility vehicle.Â Â The extended warranty covered defects occurring after the initial threeyear warranty expired.Â Â Of the 10,000 people who bought the sportutility vehicle in the first year of the program, 15% purchased the extended warranty.Â Â In the Warranty Department, you have recently received data on a random sample of 200 of the cars sold in the first year that the extended warranty was available. For this sample, the average extendedwarranty expenditure per car for the oneyear period after the initial warranty elapsed was $350., with a standard deviation of $100.
a.Â Â What is a 95 percent confidence interval for the mean oneyear extendedwarranty expenditure per automobile?
b.Â Â At its introduction, the extended warranty was priced at $224 per year per automobile.Â Â Compute a 95 percent confidence interval for the oneyear profitability of the extended warranty.
c.Â Â How large a sample would the Warranty Department require if it wanted its 95 percent confidence interval for the mean warranty expenditure to be no more than+_$5

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