SELF 12.16 More shoppers do the majority of their Test grocery shopping on Saturday than any other day of the week. However, is there a difference in the various age groups in the proportion of people who do the majority of their grocery shopping on Saturday? A study showed the results for the different age groups. (Data extracted from "Major Shopping by Day," Progressive Grocer Annual Report, April 30, 2002.) The data were reported as percent- ages, and no sample sizes were given: AGE MAJOR SHOPPING DAY Under 35 35-54 Over 54 Saturday 24% 28% 12% A day other than 76% 72% 88% Saturday Assume that 200 shoppers for each age group were surveyed. a. Is there evidence of a significant difference among the age groups with respect to major grocery shopping day? (Use ( = 0.05.) b. Determine the p-value in (a) and interpret its meaning. c. If appropriate, use the Marascuilo procedure and a = 0.05 to determine which age groups are different. d. Discuss the managerial implications of (a) and (c). How can grocery stores use this information to improve mar- keting and sales? Be specific