More shoppers do the majority of their 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 percentages, and no sample sizes were given:

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 α = 0.05.)
b. Determine the p-value in (a) and interpret its meaning.
c. If appropriate, use the Marascuilo procedure and α = 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 marketing and sales? Be specific.

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AGE 35-54 28% MAJOR SHOPPING DAY Under 35 Over 54 Saturday A day other than 24% 76% 12% 88% 72% Saturday