Suppose the Environmental Protection Agency (EPA)

would like to investigate the impact that octane has on gas mileage. The following table shows the gas mileage for six cars that were driven 1,000 miles with three different grades of gasoline: 87, 89, and 93 octane. The gas mileage was recorded for each octane level. Each car was tested with all three gasoline grades. These data can also be found in the file octane.xlsx.

Car 87 Octane 89 Octane 93 Octane Maxima 22.6 23.3 23.0 Focus 28.0 29.6 30.1 Accord 22.6 22.1 23.3 Sonata 28.6 29.1 29.4 Camry 24.1 27.7 26.0 Jetta 30.0 29.4 30.7

a. Using a = 0.05, does the octane level appear to have an effect on the gas mileage?

b. Was blocking effective? Why or why not?

c. If warranted, determine which pairs of octanes were different using a = 0.05.

d. Verify your results with Excel.

AppendixLO1