Carpenter's Mate, Inc., manufactures electric carpentry tools. The Production Department has met all production requirements for the current month and has an opportunity to produce additional units of product with its excess capacity. Unit selling prices and unit costs for three different drill models are as follows: Selling price Home Model $58 Deluxe Model Pro Model $65 $80 Direct material 16 20 Direct labor ($10 per hour) 19 10 15 20 8 12 16 16 5 15 Variable overhead Fixed overhead Variable overhead is applied on the basis of direct-labor dollars, while fixed overhead is applied on the basis of machine hours. There is sufficient demand for the additional production of any model in the product line. Required: 1-8. Calculate the contribution margin per unit for each model 1-b. If Carpenter's Mate, Inc., has excess machine capacity and can add more labor as needed (ie, neither machine capacity nor labor is a constraint), the excess production capacity should be devoted to producing which product? (Assume that the excess capacity will be used for a single product line.) 2-6. Calculate the contribution margin per direct-labor hour for each model 2-b. If Carpenter's Mate has excess machine capacity but a limited amount of labor time, the excess production capacity should be devoted to producing which product or products?