Bruce Corporation makes four products in a single facility. These products have the following unit product costs: Additional data concerning these products are listed below. The grinding machines are potentally the constraint in the production facility. A total of 33,200 minutes are avaliable per month on these machines. Direct labor is a variable cost in this company. Up to how much should the company be willing to pay for one additional minute of grinding machine time if the company has made the best use of the exlsting grinding machine capacity? (Round your intermediate calculations to 2 decimal places.)