A large automobile manufacturing company is trying to

decide whether to purchase brand A or brand B tires for its

new models. To help arrive at a decision an experiment is

conducted. The tires are run until they wear out. The results

are

Brand A: n = 18, mean = 37,900 kilometers, SD = 4100 kilometers

Brand B: n = 12, mean = 39,800 kilometers, SD = 8900 kilometers

Assume the populations to be approximately normally distributed and the population variances are unequal. You want to test the hypothesis at the 0.05 level of significance that there is no difference in the two brands of

tires.

A. Calculate the 95% C for the difference

between the population means.

• -1900.00 5887.32
• -1900.00 5766.92
• -1900.00 5980.72
• -1900.00 95
• -1900.00 + 5

B. Calculate the test statistic and P-value.

• (14) = -0.69, p = .500
• (18) =-0.69, p = .498
• +(12) =0.69, p = .502
• (14) = 0.69, p<.001
• (17) =-0.69, p = .500

C. Make the decision and summarize the results

• Do not reject HO. There's not enough evidence to reject the claim that the average distance for brand A tires is the same as the average distance for brand B tires.
• Reject HO. There's not enough evidence to reject the claim that the average distance for brand A tires is the same as the average distance for brand B tires.
• Reject HO. There's enough evidence to reject the claim that the average distance for brand A tires is the same as the average distance for brand B tires.
• Do not reject HO. There's enough evidence to support the claim that the average distance for brand A tires is not the same as the average distance for brand B tires.
• None of these choices.