Which foams more when you pour it, Coke or Pepsi? Here are measurements by Diane Warfield 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% confidence interval for the population difference in mean volumes.
c. Does the upper limit of your interval in (b) give a 99% lower confidence bound for the difference between the two μ’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.