Presented below is selected information for three regional divisions of Medina Company. Contribution margin Controllable margin Average operating assets Minimum rate of return North $300,900 $140,000 $1,000,000 12 % Divisions West $499,900 $360,000 $1,800,000 15 % South $400,600 $211,400 $1,510,000 9 % (a) Compute the return on investment for each division. North Division % West Division % South Division %