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Perfect Competition - AP Microeconomics

  1. Suppose a perfectly competitive firm faces a market price of 10.Atitscurrentoutputlevelof100units,itsaveragetotalcostis10. At its current output level of 100 units, its average total cost is14 and its average variable cost is $8. To maximize profit or minimize loss in the short run, the firm should
    Answer: continue to produce in the short run because the price covers average variable cost. The shutdown rule states that a firm should continue to operate in the short run if the price is greater than or equal to its average variable cost (P ≥ AVC). Here, 10>10 >8, so the firm should continue to produce. By producing, it can cover all its variable costs and contribute 2perunit(2 per unit (10 - $8) to paying off its fixed costs, thus minimizing its losses.
  2. Based on the perfectly competitive firm's cost and price information in the table, is the firm earning profit, loss, or normal profit at the profit-maximizing output in the short run? Assume the firm is a price taker with $P = MR = 1616. Cost Table - Fixed cost (FC) = 2828 - Variable cost (VC) by output: Q=0:0Q=0:0, 1:71:7, 2:152:15, 3:243:24, 4:354:35, 5:505:50, 6:706:70
    Answer: The firm earns an economic profit. The key skill here is understanding firm behavior in perfect competition, where firms decide output to maximize profit or minimize losses. A perfectly competitive firm is a price taker, meaning it accepts the market price as given, so its marginal revenue (MR) equals the price (P). To maximize profit, the firm produces the output level where marginal revenue equals marginal cost (MR = MC), or the largest Q where MR >= MC in discrete data. Profit or loss is determined by comparing P to average total cost (ATC) at that output, while shutdown occurs if P < average variable cost (AVC), as this means variable costs aren't covered. A common misconception is confusing short-run shutdown with long-run exit; shutdown means temporarily producing zero to avoid variable costs, while exit means permanently leaving the market. A useful strategy is to first calculate MC from changes in VC and find the Q where MR >= MC. Then, compare P to ATC for profit/loss and to AVC for shutdown decisions.
  3. Following a short-run increase in demand that leads to positive economic profits, what long-run adjustment will occur in a perfectly competitive, constant-cost industry?
    Answer: New firms will enter, increasing market supply until the price returns to its original long-run equilibrium level. The positive profits attract new firms. As new firms enter, the market supply curve shifts to the right. In a constant-cost industry, input prices do not change as the industry expands. Therefore, supply will continue to increase until the price is driven back down to the original minimum average total cost, at which point economic profits are zero again.
  4. The short-run shutdown point for a perfectly competitive firm is the output level at which
    Answer: price is equal to the minimum average variable cost. The shutdown point is the price and quantity at which the firm is indifferent between producing and shutting down. This occurs at the minimum point of the average variable cost (AVC) curve. At any price below this point, the firm cannot even cover its variable costs and will minimize its losses by shutting down (producing zero output).
  5. Which of the following correctly compares the market demand curve and the demand curve faced by a firm in perfect competition?
    Answer: The market demand curve is downward sloping, while the firm's demand curve is perfectly elastic. The market demand curve represents the relationship between the price and the total quantity demanded by all consumers in the market; it is downward sloping according to the law of demand. The demand curve for a single firm, however, is perfectly elastic (horizontal) at the market price because it is a price taker and can sell any quantity it chooses at that price.
  6. Based on the perfectly competitive firm's cost and price information in the table, should the firm shut down in the short run? Assume the firm is a price taker with $P = MR = 1111. Cost Table - Fixed cost (FC) = 2525 - Variable cost (VC) by output: Q=0:0Q=0:0, 1:91:9, 2:192:19, 3:303:30, 4:444:44, 5:655:65
    Answer: No; produce because P>AVCP > AVC at the profit-maximizing output. The key skill here is understanding firm behavior in perfect competition, where firms decide output to maximize profit or minimize losses. A perfectly competitive firm is a price taker, meaning it accepts the market price as given, so its marginal revenue (MR) equals the price (P). To maximize profit, the firm produces the output level where marginal revenue equals marginal cost (MR = MC), or the largest Q where MR >= MC in discrete data. Profit or loss is determined by comparing P to average total cost (ATC) at that output, while shutdown occurs if P < average variable cost (AVC), as this means variable costs aren't covered. A common misconception is confusing short-run shutdown with long-run exit; shutdown means temporarily producing zero to avoid variable costs, while exit means permanently leaving the market. A useful strategy is to first calculate MC from changes in VC and find the Q where MR >= MC. Then, compare P to ATC for profit/loss and to AVC for shutdown decisions.
  7. The demand curve faced by a single firm operating in a perfectly competitive market is
    Answer: perfectly elastic at the market price. A perfectly competitive firm is a price taker, meaning it can sell as much output as it wishes at the prevailing market price. If it raises its price, it sells nothing; it has no incentive to lower its price. This situation is represented by a perfectly elastic (horizontal) demand curve at the market price.
  8. The long-run supply curve for a perfectly competitive, increasing-cost industry is upward sloping because
    Answer: the entry of new firms into the market bids up the prices of essential inputs. In an increasing-cost industry, as the industry expands due to the entry of new firms, the demand for specialized inputs (like skilled labor or specific raw materials) increases. This increased demand drives up the price of those inputs, which in turn raises the cost curves (including the minimum ATC) for all firms in the industry. As a result, a higher market price is required to restore long-run equilibrium, leading to an upward-sloping long-run supply curve.
  9. If firms in a perfectly competitive industry are earning positive economic profits in the short run, which of the following will occur in the long run?
    Answer: New firms will enter the industry, causing the market supply to increase and price to fall. Positive economic profits act as a signal that attracts new firms. Because there are no barriers to entry in perfect competition, new firms will enter the industry. This entry increases the market supply, which shifts the supply curve to the right and causes the market price to fall until economic profits are competed away and return to zero.
  10. Based on the perfectly competitive firm's cost and price information in the table, should the firm shut down in the short run? Assume the firm is a price taker with $P = MR = 88. Cost Table - Fixed cost (FC) = 1616 - Variable cost (VC) by output: Q=0:0Q=0:0, 1:61:6, 2:132:13, 3:213:21, 4:324:32
    Answer: No; produce because P>AVCP > AVC at the profit-maximizing output. The key skill here is understanding firm behavior in perfect competition, where firms decide output to maximize profit or minimize losses. A perfectly competitive firm is a price taker, meaning it accepts the market price as given, so its marginal revenue (MR) equals the price (P). To maximize profit, the firm produces the output level where marginal revenue equals marginal cost (MR = MC), or the largest Q where MR >= MC in discrete data. Profit or loss is determined by comparing P to average total cost (ATC) at that output, while shutdown occurs if P < average variable cost (AVC), as this means variable costs aren't covered. A common misconception is confusing short-run shutdown with long-run exit; shutdown means temporarily producing zero to avoid variable costs, while exit means permanently leaving the market. A useful strategy is to first calculate MC from changes in VC and find the Q where MR >= MC. Then, compare P to ATC for profit/loss and to AVC for shutdown decisions.
  11. Assume a perfectly competitive firm is in long-run equilibrium. If the government imposes a new lump-sum tax on each firm in the industry, what will be the short-run effect on the firm's output and profit?
    Answer: Output will remain the same, and profit will become negative. A lump-sum tax is a fixed cost and does not affect the firm's marginal cost or marginal revenue. Since the profit-maximizing output is determined by MR = MC, the firm's output level will not change in the short run. However, the lump-sum tax increases the firm's average total cost. Since the firm was previously earning zero economic profit (P = ATC), the increase in ATC will cause the firm to incur economic losses (profit becomes negative).
  12. A firm in a perfectly competitive market sells its output for 12perunit.Atitsprofit−maximizingoutputof500units,itsaveragetotalcostis12 per unit. At its profit-maximizing output of 500 units, its average total cost is9 and its average variable cost is $7. What is the firm's total short-run economic profit?
    Answer: $1,500 Economic profit is calculated as (Price - Average Total Cost) × Quantity. In this case, profit = (12−12 -9) × 500 = $$3 × 500 = $1,500.
  13. A firm operating in a perfectly competitive market is a "price taker." This implies that if the firm tries to charge a price above the established market price, it will
    Answer: sell zero units of its product. Because all firms in a perfectly competitive market sell an identical product and there are many other sellers, a single firm has no market power. If it raises its price even slightly above the market price, rational consumers will simply buy the identical product from one of its many competitors at the lower market price. Consequently, the firm's sales will drop to zero.
  14. Based on the perfectly competitive firm's cost and price information in the table, what output level maximizes profit in the short run? Assume the market price is $P = MR = 2020. Cost Table - Fixed cost (FC) = 3636 - Variable cost (VC) by output: Q=0:0Q=0:0, 1:81:8, 2:172:17, 3:273:27, 4:404:40, 5:585:58, 6:826:82
    Answer: Q=5Q = 5 units The key skill here is understanding firm behavior in perfect competition, where firms decide output to maximize profit or minimize losses. A perfectly competitive firm is a price taker, meaning it accepts the market price as given, so its marginal revenue (MR) equals the price (P). To maximize profit, the firm produces the output level where marginal revenue equals marginal cost (MR = MC), or the largest Q where MR >= MC in discrete data. Profit or loss is determined by comparing P to average total cost (ATC) at that output, while shutdown occurs if P < average variable cost (AVC), as this means variable costs aren't covered. A common misconception is confusing short-run shutdown with long-run exit; shutdown means temporarily producing zero to avoid variable costs, while exit means permanently leaving the market. A useful strategy is to first calculate MC from changes in VC and find the Q where MR >= MC. Then, compare P to ATC for profit/loss and to AVC for shutdown decisions.
  15. The long-run market supply curve for a perfectly competitive, constant-cost industry is
    Answer: perfectly elastic because input prices remain constant as the industry expands. In a constant-cost industry, the entry or exit of firms does not affect the prices of inputs. Therefore, the long-run average cost of production remains the same regardless of the industry's size. Any increase in demand will be met by new firms entering and producing at the same minimum average total cost, resulting in a perfectly elastic (horizontal) long-run supply curve.
  16. A perfectly competitive market achieves allocative efficiency because it produces the quantity of output where
    Answer: the price that consumers are willing to pay for the last unit equals the marginal cost to produce it. Allocative efficiency occurs when resources are allocated to produce the mix of goods and services society most desires. This is achieved when the marginal benefit to society (as measured by the price consumers are willing to pay) equals the marginal cost of production. In perfect competition, firms produce where P = MC, which is the condition for allocative efficiency.
  17. Assume a perfectly competitive industry is in long-run equilibrium. If there is a permanent increase in market demand for the product, what will be the short-run effect on a typical firm in the industry?
    Answer: The firm's price, marginal revenue, and output will increase, and it will earn positive economic profit. An increase in market demand shifts the market demand curve to the right, causing the equilibrium market price to rise. Since the firm is a price taker, it now faces a higher price. This higher price is also its new, higher marginal revenue. The firm will increase its output to the new profit-maximizing level where P = MC, and since the new price is above the original ATC, it will earn positive economic profits.
  18. Based on the perfectly competitive firm's cost and price information in the table, what output level maximizes profit in the short run? Assume the firm is a price taker and the market price is $P = $18. Cost Table Quantity (Q): 0, 1, 2, 3, 4, 5, 6 Total Cost (TC): 12, 24, 34, 45, 58, 74, 96
    Answer: Produce Q=5Q = 5 units This question tests perfect competition firm behavior, where firms maximize profit by producing where marginal revenue equals marginal cost. As a price taker at P = $18, the firm's MR = $18 for each unit. Calculating marginal costs between quantities: MC from Q=4 to Q=5 is ($74-$58)/(5-4) = $16, and MC from Q=5 to Q=6 is ($96-$74)/(6-5) = $22. The firm produces where MR = MC; since $16 < $18 < $22, the optimal output is Q = 5. At this quantity, the firm earns total revenue of 5 × $18 = $90 versus total cost of $74, yielding profit of $16. A common error is choosing output based on lowest average cost rather than the MR = MC condition. The transferable strategy is: calculate MC for each interval, find where MC crosses the price level, and produce at the quantity just before MC exceeds price.
  19. To maximize its short-run profit, a perfectly competitive firm will produce the quantity of output where
    Answer: marginal revenue equals marginal cost. The universal rule for profit maximization for any firm is to produce where marginal revenue (MR) equals marginal cost (MC). For a perfectly competitive firm, price equals marginal revenue, so the rule is often stated as producing where P = MC.
  20. Productive efficiency is achieved in a perfectly competitive market in the long run because
    Answer: competition forces firms to produce at the output level that minimizes long-run average total cost. Productive efficiency means producing goods and services at the lowest possible cost per unit. In the long run, the process of entry and exit in a perfectly competitive market forces the price to the minimum point of the average total cost (ATC) curve. Firms that do not produce at this minimum cost point will incur losses and be driven out of the market.

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