ADC supermarket accepts three types of credit cards, Master card, Visa and Tembo card. The sales manager is interested in finding out whether there is a difference in the mean amounts charged by customers on the three cards. A random sample of 18 credit cards purchases revealed these credit card amounts. At the level of 0.05, using ANOVA test can we conclude that, there is a difference in the mean amounts charged per purchase on the three cards? Would Tukey-Kramer test be appropriate? Why?
Master card 61 28 42 33 51 56
Visa card 85 56 44 72 98 56 72
Tembo card 61 25 42 31 29