America’s Market Basket An advertisement for a popular supermarket chain claims that...

America’s Market Basket An advertisement for a popular supermarket chain claims that it has had consistently lower prices than one of its competitors. As part of a survey conducted by an independent price-checking company, the average weekly total, based on the prices of approximately 95 items, is given for this chain and for its competitor recorded during four 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.