America’s Market Basket An advertisement for Albertsons, a supermarket chain in the western United States, claims that Albertsons has had consistently lower prices than four other full service supermarkets. As part of a survey conducted by an “independent market basket price-checking company,” the average weekly total, based on the prices of approximately 95 items, is given for two different supermarket chains recorded during 4 consecutive
weeks in a particular month.
a. Is there a significant difference in the average prices for these two different supermarket chains?
b. What is the approximate p-value for the test conducted in part a?
c. Construct a 99% confidence interval for the difference in the average prices for the two supermarket chains. Interpret this interval.