Gas Mileage for European, Japanese, and American Cars. Use this information for Exercises 48–50. The following figure shows a comparison boxplot of the vehicle mileage (in mpg) for random samples of automobiles manufactured in Europe, Japan, and the United States. The summary statistics are provided. We are interested in testing, using , whether population mean gas mileage differs among automobiles from the three regions. Assume that the assumptions are satisfied.