Chapter 9.2, Problem 6BSC

In Exercises 5–20, assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. (Note: Answers in Appendix D include technology answers based on Formula 9-1 along with “Table” answers based on Table A-3 with df equal to the smaller of n₁ − 1 and n₂ − 1.)

6. Coke and Pepsi Data Set 26 “Cola Weights and Volumes” in Appendix B includes volumes of the contents of cans of regular Coke (n = 36, $\bar{x}$ = 12.19 oz, s = 0.11 oz) and volumes of the contents of cans of regular Pepsi (n = 36, $\bar{x}$ = 12.29 oz, s = 0.09 oz).

a. Use a 0.05 significance level to test the claim that cans of regular Coke and regular Pepsi have the same mean volume.

b. Construct the confidence interval appropriate for the hypothesis test in part (a).

c. What do you conclude? Does there appear to be a difference? Is there practical significance?