Refer to Exercise 16. Use the Tukey-Kramer procedure to identify which average purchases differ. Use a 95% level of confidence.
In exercise
The owner of a drugstore is wondering whether the amount of a customer's purchase varies by age group. The owner runs a contest with a grand prize of a $100 gift certificate that can be used in the store. The entry ballot requires the entrant to record his/her age group, and the amount of his/her most recent purchase.