Anational food product company believes that it sells more frozen pizza during the winter months than during the summer months. average weekly sales for a sample of stores in a metropolitan area over a three-year period provided the following data for sales volume (in pounds) during the two seasons. complete parts a through c. a) how much difference is there between the moan amount of this brand of frozen pizza sold (in pounds) between the two seasons? (assume that this time frame represents typical sales in the given metropolitan area.) the positive difference is 12400. b) construct and interpret a 99% confidence interval for the differences between weekly sales during the winter and summer months.