The manufacturer of a small utility trailer is interested in comparing the amount of fuel used in towing the trailer with that required to overcome the weight and wind resistance of a rooftop carrier. Over a standard test route at highway speeds, 8 trips with the trailer resulted in an average fuel consumption of 0.28 gallons, with a standard deviation of 0.03. Under similar conditions, 10 trips with the rooftop carrier led to an average consumption of 0.35 gallons, with a standard deviation of 0.05 gallons. Test the hypothesis by answering the following questions.
a. The pooled estimate of the common variance is .
b. The test statistic is .
c. The critical value of the test is .
d. At the .01 level of significance we are able to reject the null hypothesis. True
What is the critical value of the test?