Question 15. 15. At a sales volume of 20,000 units, Choice Corporation's sales commmissions (a cost that is variable with respect to sales volume) total $132,000. To the nearest whole cent, what should be the average sales commission per unit at a sales volume of 18,500 units? (Assume that this sales volume is within the relevant range.) (Points : 3) $6.60 $6.87 $7.17 $7.14