Bruce Corporation makes four products in a single facility. These products have the following unit product costs:

Products

D

Direct materials

$$14\mathrm{.}40$

$

$10\mathrm{.}30$

$$11\mathrm{.}10$

$

$10\mathrm{.}70$

Direct labor

$19\mathrm{.}50$

$27\mathrm{.}50$

$33\mathrm{.}70$

$40\mathrm{.}50$

Variable manufacturing overhead

$4\mathrm{.}40$

$2\mathrm{.}80$

$2\mathrm{.}70$

$3\mathrm{.}30$

Fixed manufacturing overhead

$26\mathrm{.}60$

$34\mathrm{.}90$

$26\mathrm{.}70$

$37\mathrm{.}30$

Unit product cost

$$64\mathrm{.}90$

$$75\mathrm{.}50$

$$74\mathrm{.}20$

$$91\mathrm{.}80$

Additional data concerning these products are listed below.

Products

Grinding minutes per unit

Selling price per unit

Variable selling cost per unit

Monthly demand in units

$3\mathrm{.}90$

$$76\mathrm{.}20$

$$2\mathrm{.}30$

$4,100$

$5\mathrm{.}40$

$ $93\mathrm{.}60$

$$1\mathrm{.}30$

$4,100$

$4\mathrm{.}40$

$ $87\mathrm{.}50$

$$3\mathrm{.}40$

$3,100$

D

$3\mathrm{.}50$

$$104\mathrm{.}30$

$ $1\mathrm{.}70$

$2,100$

The grinding machines are potentially the constraint in the production facility. A total of $58,900$ minutes are available 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 existing grinding machine capacity? $($Round your intermediate calculations to $2$ decimal places.$)$