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. At the .05 significance level, is there a difference in the gasolines orautomobiles?

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Automobile Regula Mid-grade Super Premium 21 23 24 24 26 26 28 23 25 24 26 24 27 26 25 27 26 30 27 32