Final answer:
The marginal resource cost is the extra cost a firm incurs for using one more unit of input, such as labor. In a perfectly competitive market, this is equal to the going market wage. For a firm to maximize profit, it should hire workers until the marginal revenue product of labor equals the market wage.
Step-by-step explanation:
The marginal resource cost is the additional cost incurred by a firm when they use one more unit of input, such as labor. In a perfectly competitive labor market, this cost is equal to the wage that the firm pays for labor, which is determined by the market and is the same for all firms. However, in the case of a monopsony, where the firm has some market power in hiring labor, the marginal resource cost may be higher than the wage if increasing employment requires the firm to raise wages for all employees.
In answer to the first part of the student's question: a. The value of the marginal product of labor at each level of employment is the additional revenue the firm earns from employing one more unit of labor. In the second part of the question, if the market wage is $12 and assuming the marginal revenue product (MRP) of labor is at least $12, the firm's profit-maximizing level of employment is the point at which the MRP of labor equals the market wage. However, without specific data on the MRP of labor at each level, we cannot determine the exact level of employment.