A research firm wants to compare the miles per gallon of unleaded regular, mid-grade, and super premium gasolines. Because of differences in the performance of different automobiles, seven different automobiles were selected and treated as blocks. Therefore, each brand of gasoline was tested with each type of automobile. The results of the trials, in miles per gallon, are shown in the following table (see attachment). At the .05 significance level, is there a difference in the gasolines and automobiles?
Excel sheet attached determines whether there is a difference in mpg of 3 types of gas at a 0.05 significance level.