Whole Foods is an all-natural grocery chain that has 50,000 square foot stores, up from the industry average of 34,000 square feet. Sales per square foot of supermarkets average just under $400 per square foot, as reported by USA Today in an article on "A Whole New Ballgame in Grocery Shopping."
Suppose that sales per square foot in the most recent fiscal year are recorded for a random sample of 10 Whole Foods supermarkets. The data (sales dollars per square foot) are as follows: 854, 858, 801, 892, 807, 894, 863, 829, 815.
a. Using the facts that the sample mean and the sample standard deviation are 846.2 and 32.866 respectively,
b. Find a 95% confidence interval for the population mean sales dollars per square foot for all Whole Foods supermarkets during the most recent fiscal year. Assume normality. (Be sure to show your work.)
c. Are we 95% confident that this population mean is greater than $800, the historical Whole Foods? Explain.