29. Which foams more when you pour it, Coke or Pepsi? Here are measurements by Diane War eld on the foam volume (mL) after pouring a 12-oz can of Coke, based on a sample of 12 cans:

312.2 292.6 331.7 355.1 362.9 331.7 292.6 245.8 280.9 320.0 273.1 288.7 and here are measurements for Pepsi, based on a sample of 12 cans:

148.3 210.7 152.2 117.1 89.7 140.5 128.8 167.8 156.1 136.6 124.9 136.6

a. Verify graphically that normality is an appropriate assumption.

b. Calculate a 99% con dence interval for the population difference in mean volumes.

c. Does the upper limit of your interval in

(b) give a 99% lower con dence bound for the difference between the two m s? If not, calculate such a bound and interpret it in terms of the relationship between the foam volumes of Coke and Pepsi.

d. Summarize in a sentence what you have learned about the foam volumes of Coke and Pepsi.