Use the Hannaford data to complete the following:

a. Create three new variables that include values for the difference in total expenditures after and before the holiday, after and during the holiday, and during and before the holiday.

b. Estimate 95% confidence intervals for the means of each of the variables you calculated in a).

c. What are the standard errors used in the Margins of Error?

d. Create a bar graph that includes the average differences you generated for part a) and superimpose whiskers that represent the confidence intervals you calculated in b).NOTE: You should not have a second set of bars for the standard deviations.

e. Explain what your chart shows.