13. A rm is currently employing a cost-minimizing combination of labor and capital for a given level of output. The rm is employing 20 workers, and the marginal product of the last worker is 40 units of output. The rm is employing 100 units of capital, and the marginal product of the last unit of capital is 10 units of output. If the wage rate is $20 per hour, what is the price of capital? Page 4 of 7 AP Microeconomics m Test Booklet Unit 5 test (A) $2.5 per hour (B) $5 per hour (C) $10 per hour (D) $100 per hour (E) $200 per hour