The Tire Rack, America's leading online distributor of tires and wheels, conducts extensive testing to provide customers with products that are right for their vehicle, driving style, and conditions in which they drive. In addition, they have maintained an independent consumer survey to help drivers help each other by sharing their long-term tire experiences.

The data shown below show survey ratings (1 to 10 scale with 10 the highest rating) for two all-season passenger tires, the Dunlop SP60 and the Michelin MX4 (Tire Rack website, April 18, 2008).

Dunlop

Michelin

a. Formulate the hypotheses that can be used to determine whether the sample data support the hypothesis that the mean rating for Dunlop SP60 tires is greater than the mean rating for Michelin MX4 tires.
b. What is the point estimate of the difference between the means for the two populations?
c. Compute the p-value for the hypothesis test.
d. At α = .05, what is your conclusion?

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.7 8.1 9.18.6 74 8397 95 9.0 8.2 98 8.0 10.0 8593 7.7 8.9 9.6 7910.0 83 8.1 5. 3 8.0 8.5 9.4 76 84 4.2 76 5.9 8.0 7.2 7.1 44 85 6.6 74 95 66 8.0 8.9 8.6 5.9 7.2 66 23 7.7 76 7.3 86 818.9 9.0 8.0 8.66 6.9 8.1 3.9 5.2 66 6.0 6.4 83 66 348.4