A major oil company has developed a new gasoline additive that is supposed to increase mileage. To test this hypothesis, ten cars are randomly selected. The cars are driven both with and without the additive. The results are displayed in the following table. Can it be concluded, from the data, that the gasoline additive does significantly increase mileage?

Let d=(gasmileagewithadditive)(gasmileagewithoutadditive)

d=(gasmileagewithadditive)(gasmileagewithoutadditive). Use a significance level of =0.05

=0.05 for the test. Assume that the gas mileages are normally distributed for the population of all cars both with and without the additive.

Car12345678910Without additive20.7

20.718.1

18.111.7

11.713

1311.7

11.718

1815.4

15.424.5

24.525.8

25.828.1

28.1With additive24.2

24.221.6

21.613

1314.5

14.512.7

12.719.6

19.615.9

15.927.1

27.127.7

27.729.5

29.5

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Step1of5:State the null and alternative hypotheses for the test.