Bruce Corporation makes four products in a single facility. These products have the following unit product costs: Direct materials Direct labor Variable manufacturing overhead Pixed manufacturing overhead Unit product cont Products B D $19.90 $15.20 $20.80 $23.20 12.20 8.70 10.50 7.40 1.60 2.10 2.00 2.10 10.80 11.90 8.80 10.70 $44.50 $37.90 $42.10 $43.40 Additional data concerning these products are listed below. Grinding minutes per unit Selling price per unit Variable selling cost per unit Monthly demand in units Products B C D 1.20 0.70 0.60 0.60 $59.30 $51.70 $59.50 $55.60 $ 3.60 $ 1.50 $ 2.20 $ 3.60 4,000 2,000 4,000 2,000 The grinding machines are potentially the constraint in the production facility. A total of 9,000 minutes are available per month on these machines. Direct labor is a variable cost in this company, How many minutes of grinding machine time would be required to satisfy demand for all four products