- A firm in a competitive market is maximizing its profit. If the market price for its product is $40, what can be concluded about the firm's marginal cost (MC) and average total cost (ATC)?
Answer: MC is approximately $40, and ATC is less than or equal to $40.
A profit-maximizing firm in a competitive market produces at the quantity where Price (Marginal Revenue) equals Marginal Cost. Therefore, its MC must be approximately $40. For the firm to be profitable (or break even) and continue operating in the long run, the price must also be greater than or equal to its Average Total Cost. We cannot conclude that ATC is exactly $40 (which would mean zero economic profit), only that it cannot be greater than $40 if the firm is earning a profit or breaking even.
- A technological innovation allows a car manufacturer to produce vehicles with fewer labor hours per car. Assuming autoworker wages remain constant, how will this change affect the manufacturer's marginal cost (MC) curve?
Answer: The MC curve will shift downward because the variable cost per unit of output has decreased.
Marginal cost is driven by changes in variable costs. Labor is a key variable cost. If fewer labor hours are needed to produce each car, the labor cost per car decreases. This reduction in the marginal cost of production for every level of output causes the entire marginal cost curve to shift downward (or to the right).
- A bakery's marginal cost of producing cakes begins to increase after the 20th cake due to the law of diminishing marginal returns. This phenomenon occurs in the short run because:
Answer: a fixed input, such as the number of ovens, becomes constrained as variable inputs like labor are added.
The law of diminishing marginal returns states that as more units of a variable input (like bakers) are added to a fixed input (like ovens), the marginal product of the variable input will eventually decline. This means each additional baker adds less to total output than the one before. To get one more unit of output, the firm must incur the same variable cost (e.g., a baker's wage) for less additional output, causing the marginal cost per unit of output to rise.
- Which of the following events would cause a firm's marginal cost curve to shift upward?
Answer: A law requiring the firm to pay its workers a higher hourly wage.
Marginal cost is affected by changes in variable costs. An increase in the hourly wage raises the cost of labor for each unit produced, thus increasing the marginal cost at every level of output. This is represented by an upward shift in the marginal cost curve. An increase in rent is a fixed cost and does not affect MC. A more productive manager would lower MC. A change in the product's price affects marginal revenue, not marginal cost.
- Due to a new trade agreement, the price of imported steel, a key input for an automobile manufacturer, decreases significantly. Holding all else constant, how will this affect the manufacturer's marginal cost (MC) curve and its profit-maximizing quantity of cars (Q)?
Answer: MC curve shifts downward; Q increases.
Steel is a variable cost in the production of automobiles. A decrease in the price of a key input lowers the cost of producing each additional car. This causes the firm's marginal cost curve to shift downward. A profit-maximizing firm produces where marginal revenue (the price of the car) equals marginal cost. With a lower MC curve, the intersection with the fixed MR curve occurs at a higher quantity. Thus, the firm will increase its profit-maximizing quantity of output.
- A restaurant owner is deciding whether to stay open for one extra hour at the end of the day. The expected revenue from that hour is $200. The costs for that hour are $75 for staff wages, $40 for utilities, and $25 for food supplies. The restaurant's monthly rent is $6,000. The owner should:
Answer: stay open, because the marginal revenue of $200 exceeds the marginal cost of $140.
The decision should be based on marginal analysis. The marginal revenue of staying open is the additional revenue earned, which is $200. The marginal cost is the sum of the additional costs incurred for that specific hour: $75 (wages) + $40 (utilities) + $25 (food) = $140. The monthly rent is a fixed cost and is irrelevant to this marginal decision. Since marginal revenue ($200) is greater than marginal cost ($140), staying open for the extra hour will add $60 to the restaurant's profit.
- A firm's total cost to produce 40 units is $2,000. Its total cost to produce 41 units is $2,055. If the firm operates in a perfectly competitive market and the current market price is $50, which of the following decisions would maximize the firm's profit?
Answer: The firm should decrease production because its marginal cost is greater than its marginal revenue.
First, calculate the marginal cost (MC) of the 41st unit: MC = Change in Total Cost / Change in Quantity = ($2,055 - $2,000) / (41 - 40) = $55. In a perfectly competitive market, price equals marginal revenue (MR), so MR = $50. Since the MC of the 41st unit ($55) is greater than the MR ($50), producing that unit would decrease profit. Therefore, the firm should decrease production from 41 units (or not increase it from 40). Note that at 40 units, ATC is $50, which equals the price. This means profit is zero, but the key is the marginal decision.
- An airline is deciding whether to sell one more seat on a flight from New York to Los Angeles. The flight is already scheduled to depart and has empty seats. Which of the following most accurately represents the marginal cost of selling that one additional seat?
Answer: The cost of the additional snacks and beverages the passenger will consume.
Marginal cost is the additional cost incurred from one more unit of output (one more passenger). The major costs of the flight (fuel, crew, airport fees, maintenance) are fixed or have already been committed once the flight is scheduled. They do not change if one more passenger boards. The only true additional costs are the variable costs directly associated with that passenger, such as the snacks, drinks, and a small amount of extra fuel. Among the choices, this is best represented by the cost of snacks and beverages.
- The short-run supply curve for a firm in a perfectly competitive industry is its marginal cost curve, but only the portion that lies above the minimum point of its:
Answer: average variable cost curve.
A firm will produce as long as the revenue from selling a unit (the price) covers the variable costs of making that unit. The average variable cost (AVC) represents the per-unit variable cost. If the price falls below the minimum AVC, the firm is better off shutting down in the short run because it would lose less money (only its fixed costs) than it would by producing. Therefore, the firm will only supply goods at prices equal to or above its minimum AVC, making that portion of its MC curve its supply curve.
- A key distinction between a firm's short-run and long-run production decisions is that in the long run, the marginal cost of increasing output can include:
Answer: the cost of expanding the factory or acquiring more machinery.
In the short run, at least one input (typically capital, like the factory size) is fixed. Decisions are made by varying inputs like labor and materials. In the long run, all inputs are variable. Therefore, a decision to increase output in the long run can involve changing the scale of the entire operation, including expanding the factory or buying more machines. These costs, which were fixed in the short run, become part of the marginal decision-making process for large-scale changes in the long run.
- A firm is producing widgets in a competitive market where the price is $20. At its current output level, the firm's marginal cost is $22 and its average total cost is $15. To maximize profit, the firm should:
Answer: decrease its output, because the cost of the last unit produced exceeded its revenue.
Profit is maximized where marginal revenue (MR) equals marginal cost (MC). In a competitive market, price equals marginal revenue, so MR = $20. Since the current MC is $22, MR < MC. This means the last unit produced cost more to make ($22) than it generated in revenue ($20), reducing total profit. Therefore, the firm should decrease its output to the point where MR = MC.
- A book publisher has a contract with an author to pay a $5,000 advance plus a royalty of $3 for every book sold. The cost of paper, printing, and binding is $4 per book. What is the publisher's marginal cost for producing one additional book?
Answer: $7
Marginal cost is the additional cost to produce one more unit. The $5,000 advance is a fixed cost; it is paid regardless of how many books are sold and does not change with the production of one more book. The variable costs that change with each additional book are the printing costs ($4) and the author's royalty ($3). Therefore, the marginal cost is the sum of these variable costs: $4 + $3 = $7.
- A government decides to provide a per-unit subsidy to producers of electric bicycles. How does this policy affect a typical firm's marginal cost (MC) curve and its profit-maximizing quantity (Q)?
Answer: The MC curve shifts downward, and Q increases.
A per-unit subsidy effectively lowers the cost of producing each additional unit. This means the firm's marginal cost for any given quantity is now lower than before. A lower marginal cost is represented by a downward shift of the MC curve. Since the firm maximizes profit where MR = MC, a lower MC curve will intersect the MR curve at a higher quantity of output. Therefore, the profit-maximizing quantity increases.
- A local government imposes a new, flat $500 annual license fee on all food trucks operating in the city. How will this new fee affect a single food truck's marginal cost (MC) and its profit-maximizing number of meals to sell (Q) in the short run?
Answer: MC remains the same, and Q remains the same.
The annual license fee is a fixed cost; it does not change with the number of meals sold. Marginal cost is the change in total cost from producing one more unit. Since the fee does not vary with output, it does not affect the marginal cost. The profit-maximizing quantity is determined by the intersection of marginal cost and marginal revenue. As neither the marginal cost curve nor the market price (marginal revenue) has changed, the profit-maximizing quantity of meals also remains the same. The fee will, however, reduce the truck's overall profit.
- If a firm's marginal cost is rising, but it is still below its average total cost, what must be happening to the average total cost?
Answer: Average total cost must be falling.
The relationship between marginal and average values is a rule of mathematics. As long as the marginal value (the cost of the next unit) is below the average value, it will pull the average down. Even if the marginal cost is rising, as long as it has not yet reached the level of the average total cost, the average will continue to decrease. ATC only begins to rise when MC crosses it from below.
- A firm experiences diminishing marginal returns. This implies that:
Answer: its marginal cost is increasing.
Diminishing marginal returns means that each additional unit of a variable input (like a worker) adds less to total output than the previous unit. Since the cost of each additional worker (the wage) is constant, but the output from that worker is falling, the cost per additional unit of output must be rising. This is the definition of increasing marginal cost.
- A company hires a new programmer at a salary of $8,000 per month. With this new hire, the company's monthly output of coded features increases from 18 to 22. What is the marginal cost per feature associated with this decision?
Answer: $2,000.00
Marginal cost is the change in total cost divided by the change in quantity. The change in total cost is the programmer's salary, $8,000. The change in quantity (output) is 22 - 18 = 4 features. Therefore, the marginal cost per feature is $8,000 / 4 = $2,000.
- A competitive firm is producing at a quantity where the market price is $12, its marginal cost is $12, its average total cost is $14, and its average variable cost is $10. What is the firm's best short-run strategy?
Answer: Continue producing at the current level, despite making an economic loss.
The firm is maximizing profit (or minimizing loss) because price (MR) equals marginal cost ($12). The firm should only shut down if the price is below the average variable cost (AVC). Here, the price ($12) is greater than the AVC ($10). This means that for each unit sold, the revenue covers all variable costs and contributes $2 toward paying fixed costs. While the firm is making an overall economic loss (since P < ATC), shutting down would result in losing all of its fixed costs, which is a greater loss than continuing to operate.
- A profit-maximizing firm in a competitive market is producing 500 units. At this output, its marginal revenue is $30, its marginal cost is $30, and its average total cost is $25. What is the firm's total profit?
Answer: $2,500
The firm is producing at the profit-maximizing quantity where MR = MC. To find total profit, we calculate the profit per unit and multiply by the quantity. Profit per unit = Price (or MR) - Average Total Cost = $30 - $25 = $5. Total Profit = Profit per unit × Quantity = $5 × 500 = $2,500. The fact that MR=MC tells us the firm is at the correct output level, not that its profit is zero.
- A company that manufactures drones spent $2 million on research and development. The factory is now operational. The marginal cost to produce each drone is $150, which includes parts and labor. Due to intense competition, the market price for the drone has dropped to $140. Which course of action should the firm take regarding production?
Answer: Do not produce any drones because the price is less than the marginal cost of production.
Production decisions should be based on marginal analysis. The $2 million spent on R&D is a sunk cost and should not influence the decision to produce more units. The decision hinges on comparing the marginal revenue (the price of $140) with the marginal cost ($150). Since MR < MC, producing each drone would lose the company an additional $10. Therefore, the profit-maximizing (or loss-minimizing) decision is to produce zero drones.
