Presented below is selected information for three regional divisions of Medina Company. Divisions North West South Contribution margin $299,900 $500,000 $399,900 Controllable margin $141.000 $360,000 $210,000 Average operating assets $940,000 $1,800,000 $1,400,000 Minimum rate of return 11 % 14 % 9 % (a) Compute the return on investment for each division. North Division % West Division South Division %