QSR magazine reports on the largest quick serve and fast casual restaurants in the United States. Do the various market segments (burger, chicken, sandwich, and pizza) differ in their mean sales per unit? The file Fast Food Chain contains the mean sales in a recent year. (Data extracted bit.ly/1mw56xA.)

a. At the 0.05 level of significance, is there evidence of a difference in the mean U. S. mean sales per unit ($ thousands) among the food segments?

b. At the 0.05 level of significance, is there a difference in the variation in U. S. average sales per unit ($ thousands) among the food segments?

c. What effect does your result in (b) have on the validity of the results in (a)?