Brand A gasoline was employed in 16 similar automobiles under identical conditions. The corresponding sample of 16 values (miles per gallon) had mean 19.6 and standard deviation 0.4. High-power brand B gasoline was tested under identical conditions using another batch of 16 similar automobiles. The test results gave a sample of 16 values with mean 20.2 and standard deviation 0.6. Is the mpg of B significantly better than that of A? Test at 5% and assume normality.