Problem 3: If a K-Mart customer buys on average 5 times a month, how much is the AIT for this customer? Approximately, how often does the customer do shopping in the K-Mart? Problem 4: The Giant Eagle had acquired 6,000 new customers at the beginning of January 2007 through one marketing campaign. By the end of December, 2007, only 2,200 of these customers still kept shopping at Giant Eagle. How much was the retention rate in 2007 ? How long is the average customer lifetime duration? Problem 5 : The activities of three Giant Tiger customers are recorded in Table 1. In the table, 1 stands for transaction for each customer and 0 stands for no transaction for each customer. What's the probability at which each customer will do shopping in September and November, respectively