Question: The average mpg usage for a 2004 Ford Expedition 2WD for a sample of 10 tanks of gas was 17.0 with a standard deviation of 0.8. For a Ford Explorer 2WD, the average mpg usage for a sample of 10 tanks of gas was 18.5 with a standard deviation of 1.0. (a) Assuming equal variances, at α = .01, is the true mean mpg lower for the Ford Expedition? (b) Calculate the p-value using Excel. (Data are from www.fueleconomy.gov .)