3. Automobiles manufactured by the Efficiency Company have been averaging 42 miles per gallon of gasoline in highway driving. It is believed that its new automobiles average more than 42
miles per gallon. An independent testing service road-tested 36 of the automobiles. The sample
showed an average of 42.8 miles per gallon with a standard deviation of 1.2 miles per gallon.
With a 0.05 level of significance using the p-value approach, test to determine whether or not
the new automobiles actually do average more than 42 miles per gallon.
a.
State the null and alternative hypotheses. (10 points)
b.
Compute the test statistic. (10 points)
c.
What is the p-value associated with the sample results? What is your conclusion
based on the p-value? (10 points)