[Next four questions] A bank conducted a profitability analysis in retail banking. It is found that the profitability depends heavily on whether the customer uses online banking frequently or not. The bank divides customers into two groups: those who use online banking frequently (Group A) and those who don't (Group B). The profitability of Group A customers is represented by a random variable X with mean $400 and a standard deviation of $80, and Group B profitability is represented by random variable Y with mean $300 and a SD of $50. If 60% customers belong to Group A and 40% belong to Group B, then 37. What is the mean profitability per customer? " m . 400 & . go a. $320 0.4 B M - 300 650 b. $340 (C. $360 2100 + 1200 = 3600 d. $380 38. Assume customers are independent of each other. What is the standard deviation of profitability for a randomly selected customer? a. $42 orpipe Meah A 400 4000 b. $52 50 101500 c. $62 30D d. $72 39. If the bank is considering a plan to increase customer profitability. After implementation of the plan, it is estimated that average profitability of Group A customers will increase by $15, and Group B will increase by $5. The cost of implementing the plan is $6 per customer. What is the net gain per customer from the plan? A. $5 B. $6 C. $7 D. $8