Refer to your analysis for Develop Your Skills 11.2, Exercise 7 (page 420). Which group of customers has the highest average purchases?
In exercise
The owner of a winery is wondering whether the average purchase of visitors to her winery differs according to age. She asks the cashiers to keep track of a random sample of purchases by customers in three age groups: under 30, 30–50, over 50. Because there is no good reason to ask a customer his or her age, the cashiers guess which age group a customer belongs to (and if they do not guess accurately, the research may not be helpful).