Datafile Apple Purchase History shows the first and second purchases for a sample of 200 customers who have made repeat purchases. Table 10.1 is a PivotTable of Apple Purchase History showing the cross-tabulation of counts between the first purchase and the second purchase, as in Table 10.1 below (also see Fig. 5.5, p.182). Table 10.1. PivotTable. Counts of cross-tabulation between 1st purchase and 2nd purchase First Purchase Second Purchase Grand total iMac iPad iPhone iPod MacBook iMac 2 3 2 6 13 iPad 1 1 2 10 14 iPhone 3 4 14 21 42 iPod 3 12 12 30 57 MacBook 8 16 26 24 74 Grand total 15 34 42 42 67 200 (1) Divide each number in Table 10.1 by the grand total 200, we have the following table (fill up Table 9.2): Table 10.2. Joint Probabilities and Marginal Probabilities First Purchase Second Purchase Grand total iMac iPad iPhone iPod MacBook iMac iPad iPhone iPod MacBook Grand total (e) P(1st purchase is iPhone | 2nd purchase is MacBook) =