The marginal product of labor is the change in output that results from an additional unit of labor. In this case, the marginal product of the fourth unit of labor would be the difference between the total output of production with four units of labor and the total output of production with three units of labor, which is 5 units.

Imposing a minimum wage usually causes a price floor in the market. Thus, the labor market for coal miners will likely see a surplus, which typically occurs when there is a price floor. The price will be higher than the equilibrium, which means that the labor supply will be greater than demand.

Variable costs associated with production are costs that change in proportion to the level of production. By contrast, fixed costs are costs that are not dependent on production level. Fixed costs and variable costs make up a good's total cost of production.

In this case, the total cost of producing zero units is 12. The total variable cost of producing zero units is 0, which means that 12 must be the fixed cost associated with producing this good.

The total cost of producing 5 units is 33. Since total costs subtracted by fixed costs equals its variable costs, the variable cost of producing 5 units must be 21.

Marginal product of labor describes how the total product of labor changes when more labor is hired. If the total product of labor is rising as labor increases, then the marginal product of labor must be increasing.

To maximize profits, a perfectly competitive firm will hire until its marginal revenue of labor equals its marginal cost of labor. The marginal cost of labor equals the wage rate, which is $14 per hour.

The marginal revenue of labor is the marginal product of labor multiplied by the price of the good. Since the marginal product at the profit maximizing level is 7 units per hour, the market price of the good must be $2 (7 units multiplied by $2 equals $14).

Hot dogs and hot dog buns are a model pair of complementary goods. Few people buy one without buying the other. You can graph the situation described using supply and demand curves for each market.

In the hot dog market, a significant decrease in supply will result in an inward shift of the supply curve which results in a higher price and fewer hot dogs being bought and sold.

The resulting effect in the market for hot dog buns, with fewer hot dogs being sold, is an inward shift in the demand curve, which results in a decrease in both the market price and quantity sold of hot dog buns.

Graph supply and demand curves to represent the market for cotton. The changes described would result in an outward shift of both the supply and demand curves. The new equilibrium would clearly have an increase in the quantity traded, but the equilibrium price would depend on the slope of the curves. Therefore, without more information, the effect on the market price is indeterminate.

A sugar beet crop failure would result in an inward shift of the supply curve in the market for sugar beets, resulting in a higher equilibrium price.

Since sugar beets and sugar cane are substitutes, this would result in greater demand for sugar cane, which would result in a higher price for sugar cane as well.

First, an increase in the supply of sugar beet results in a lower market price, and therefore lower demand for sugar cane, since they are substitutes. This translates into a lower market price and lower quantity traded for sugar cane.

Second, the increased supply of sugar cane would result in a lower market price and higher quantity traded in sugar cane. Therefore, the market price would definitely decrease, but the direction of the change in quantity cannot be determined.

As seen in the graph below, the monopolist faces a downward sloping marginal revenue curve that is steeper than the demand curve. The monopolist produces where MC = MR which results in a higher price and lower output compared to where the marginal cost curve meets the demand curve, which is where equilibrium would be in a perfectly competitive market.