CLEP Principles of Microeconomics — Mock Exam

Answer Key

1. B) human wants exceed the resources available to satisfy them. Scarcity is the universal gap between unlimited wants and limited resources — it applies to every society, rich or poor. Distractors: A) inequality is a distribution issue, not the definition of scarcity. C) government failure is one possible response to scarcity, not its cause. D) deliberate output limits describe monopoly behavior, not scarcity. E) disasters destroy resources but scarcity exists even with none. Fix: Scarcity = limited means versus unlimited wants; it exists even in wealthy, well-run economies. [Understand]

2. D) supply to decrease, raising price and reducing quantity. Oranges are an input to orange juice; destroying the crop raises input cost, shifting OJ supply left. Price rises, equilibrium quantity falls. Distractors: A) a demand shift is wrong; the shock hits the input (supply) side. B) supply falls, not rises. C) demand does not change from a supply-side input shock. E) a single leftward supply shift moves price up unambiguously. Fix: A rise in the price/scarcity of an input shifts supply left → higher price, lower quantity. [Apply]

3. E) horizontal at the market price. A price taker can sell any quantity at the going price, so its individual demand is perfectly elastic (horizontal) at that price. Distractors: A) a downward-sloping firm demand describes a price maker. B) demand curves are never upward sloping. C) the firm's demand is horizontal even though the market demand slopes down. D) vertical would mean perfectly inelastic — the wrong axis. Fix: Perfect competition → the firm's own demand is flat at the market price; MR = P. [Understand]

4. D) the marginal utility per dollar spent is equal across all goods. The utility-maximizing rule is MUx/Px = MUy/Py; the last dollar buys equal extra utility everywhere. Distractors: A) equal total utility ignores prices. B) equal marginal utility ignores prices too — only right if prices are identical. C) "highest total utility" describes the goal, not the marginal condition. E) equal prices are neither required nor sufficient. Fix: Optimize on the margin per dollar: set MU/P equal across goods, not MU or total utility. [Apply]

5. C) the law of diminishing marginal returns. Adding a variable input (labor) to a fixed input (capital) eventually lowers each added worker's extra output — a short-run phenomenon. Distractors: A) diseconomies of scale are a long-run effect when all inputs grow. B) the law of demand is about price and quantity demanded. D) constant returns to scale is a long-run, all-inputs concept. E) economies of scale would lower average cost, not marginal product. Fix: Fixed input + more of a variable input = diminishing marginal returns (short run); scale effects need all inputs to vary. [Understand]

6. A) overproduce, because the firm ignores the external cost it imposes on others. With a negative externality, marginal social cost exceeds marginal private cost, so the market quantity is above the efficient quantity. Distractors: B) pollution is an external cost the firm does not bear, so it does not restrain output. C) an unpriced externality is precisely what the market fails to internalize. D) this is a negative externality (cost), not a benefit. E) that reasoning fits a positive externality (underproduction). Fix: Negative externality → MSC > MPC → market overproduces relative to the social optimum. [Apply]

7. B) an increase in the demand for cream, raising its price. A lower coffee price raises coffee quantity; since cream complements coffee, demand for cream shifts right, raising cream's price. Distractors: A) the cheaper good (coffee) moves along its curve, but cream's whole demand curve shifts. C) complements move together — a fall in coffee's price raises cream demand, not lowers it. D) the effect is on cream's demand, not its supply. E) complements are related, so there is a definite effect. Fix: Complements move together: a price drop in one raises demand for the other. [Analyze]

8. E) below average variable cost. In the short run a firm shuts down when price cannot cover average variable cost; below AVC, producing loses more than the fixed cost it would owe anyway. Distractors: A) P below ATC means a loss but the firm keeps producing if P ≥ AVC. B) P below MC just means produce a bit less, not shut down. C) P = MR always holds in competition and says nothing about shutdown. D) between AVC and ATC the firm operates at a loss but does not shut down. Fix: Short-run shutdown rule: produce if P ≥ AVC; shut down only when P < AVC. [Understand]

9. C) the marginal product of labor multiplied by marginal revenue (the output price, in competition). MRP = MPL × MR; in perfect competition MR = P, so MRP = MPL × P — the value of the extra output a worker makes. Distractors: A) dividing wage by output is not MRP. B) that is average revenue product, not marginal. D) MPL divided by the wage has no standard meaning here. E) the change in total cost from a worker is marginal factor cost, not MRP. Fix: MRP = MPL × MR (= MPL × P in competition); it is the labor-demand curve. [Remember]

10. A) the $60 in forgone wages (the value of the best alternative given up). Opportunity cost is the value of the next-best forgone option — here, the wages the student passed up. Distractors: B) time has value; the forgone shift is a real cost. C) tuition is a sunk cost already paid, not the cost of this evening. D) total savings are unrelated to this specific choice. E) the enjoyment is a benefit of studying, not its cost. Fix: Opportunity cost = value of the best alternative forgone, not money outlays or sunk costs. [Apply]

11. D) demand to increase, raising price and quantity. Beef and chicken are substitutes; a higher chicken price sends buyers to beef, shifting beef demand right → higher beef price and quantity. Distractors: A) the shock affects demand, not beef supply. B) beef supply is unchanged. C) substitutes move in the same direction as the other good's price, so demand rises, not falls. E) a whole-curve shift, not a movement along it, occurs. Fix: Substitutes: a rise in one good's price raises demand for the other. [Apply]

12. B) new firms enter, market supply rises, and price falls until economic profit is zero. Free entry in competition erodes short-run profits; entry continues until price = minimum ATC and profit = 0. Distractors: A) no barriers exist in perfect competition, so profits cannot persist. C) firms exit when there are losses, not profits. D) price takers cannot raise price. E) demand need not fall; entry does the work. Fix: Competitive profits attract entry → supply up, price down → long-run zero economic profit. [Analyze]

13. E) the monthly lease payment on the building. A fixed cost does not vary with output in the short run; the lease is owed whether the bakery makes 0 or 1,000 loaves. Distractors: A) flour rises with output — variable. B) hourly wages scale with production — variable. C) oven electricity rises with output — variable. D) packaging boxes vary with quantity sold — variable. Fix: Fixed cost = unchanged by output in the short run (rent, insurance); variable cost rises with output. [Apply]

14. C) nonrival and nonexcludable. A public good can be consumed by one person without reducing others' consumption (nonrival) and cannot easily exclude non-payers (nonexcludable). Distractors: A) public goods can be privately provided; the definition is about rivalry/excludability, not the provider. B) rival and excludable describes an ordinary private good. D) production is not free. E) rival-but-nonexcludable describes a common resource, not a public good. Fix: Public good = nonrival + nonexcludable; common resource = rival + nonexcludable. [Remember]

15. A) demand to increase, raising equilibrium price and quantity. For a normal good, higher income shifts demand right, pushing both equilibrium price and quantity up. Distractors: B) demand falls with income only for inferior goods. C) income shifts demand, not supply. D) an income change shifts the whole curve, not a movement along it. E) income is a demand determinant, so there is an effect. Fix: Normal good + higher income → demand shifts right → P and Q both rise. [Apply]

16. D) less output at a higher price. A single-price monopoly restricts output (MR = MC below the competitive quantity) and charges a price above marginal cost — less output, higher price than competition. Distractors: A) reverses both effects. B) output differs (it falls), so "same output" is wrong. C) output falls and price rises. E) price is higher, not lower. Fix: Monopoly vs. competition: less Q, higher P, P > MC (deadweight loss). [Analyze]

17. B) marginal utility — high for scarce diamonds, low for abundant water. Price tracks marginal utility. Water is abundant, so its marginal unit is worth little; diamonds are scarce, so their marginal unit commands a high price despite low total usefulness. Distractors: A) total utility of water is huge yet its price is low — total utility does not set price. C) the labor theory of value is not the marginalist answer tested here. D) these are competitive market prices, not set by government. E) water clearly has utility; its marginal value is just low. Fix: Prices reflect marginal, not total, utility — the diamond–water paradox. [Analyze]

18. E) increasing opportunity cost as more of one good is produced. A bowed-out PPF has a slope that steepens as you shift toward one good, meaning each extra unit costs more of the other — increasing opportunity cost. Distractors: A) constant opportunity cost gives a straight-line PPF. B) unemployment is shown by a point inside the curve, not its shape. C) growth is an outward shift of the curve. D) points on the curve are attainable and efficient. Fix: Bowed-out PPF = increasing opportunity cost; straight-line PPF = constant opportunity cost. [Understand]

19. C) 4 units at $7. Total revenue is 10, 18, 24, 28, 30, so marginal revenue is 10, 8, 6, 4, 2. Produce while MR ≥ MC ($4): through the 4th unit (MR = 4). Price comes from the demand schedule at 4 units = $7. Distractors: A) the 5th unit has MR = 2 < MC = 4, a loss on that unit. B) stopping at 3 leaves the profitable 4th unit's MR = MC opportunity on the table. D) right quantity, but price is read off the demand curve ($7), not set at MC. E) far too little output. Fix: Build the MR column, produce until MR = MC, then read price up on the demand curve — never off MR. [Apply]

20. A) rise, but the change in quantity is indeterminate. Higher demand and lower supply both push price up (unambiguous). Demand raises quantity while supply lowers it, so net quantity depends on relative shift sizes — indeterminate. Distractors: B) price rises, not falls. C) two same-direction price pressures cannot leave price unchanged. D) price rises, not falls. E) quantity is indeterminate, not definitely up. Fix: Demand up + supply down → price definitely up, quantity ambiguous. (Draw both shifts to see the ambiguous variable.) [Analyze]

21. D) $30. Variable cost = total cost − fixed cost = $2,000 − $500 = $1,500. AVC = $1,500 / 50 = $30. Distractors: A) $40 is average total cost ($2,000/50). B) $10 is average fixed cost ($500/50). C) $50 has no basis in the numbers. E) $25 misdivides. Fix: AVC = (TC − FC) / Q; keep AVC, AFC, and ATC straight (ATC = AVC + AFC). [Apply]

22. B) earns zero economic profit, producing where price equals average total cost but above marginal cost. Free entry competes away profit, so P = ATC in the long run, but differentiated demand slopes down, so P > MC (excess capacity). Distractors: A) differentiation does not protect long-run profit when entry is free. C) it does not reach minimum ATC — that is the excess-capacity result. D) P > MC, not equal, because demand slopes down. E) monopolies can keep profit; monopolistic competitors cannot. Fix: Monopolistic competition long run: P = ATC (zero profit) but P > MC (inefficient, excess capacity). [Understand]

23. E) the wage equals the marginal revenue product of labor. A firm hires until the extra revenue a worker brings (MRP = MPL × P) equals the wage it pays. Distractors: A) average product is not the hiring margin. B) maximizing MPL is not the profit rule. C) maximizing total revenue ignores labor cost. D) using MPL in physical units omits the output price — the classic slip. Fix: Hire until w = MRP (= MPL × output price), the value the marginal worker adds. [Understand]

24. A) grant a per-unit subsidy equal to the marginal external benefit. A positive externality means the market underproduces; a subsidy equal to the external benefit shifts the market to the efficient quantity. Distractors: B) a tax would cut output further below the efficient level — wrong direction. C) a ceiling causes shortages and does not fix underprovision. D) banning eliminates the good entirely. E) doing nothing leaves the market below the efficient quantity. Fix: Positive externality → subsidize to expand output; negative externality → tax to shrink it. [Apply]

25. C) inelastic. When a price increase raises total revenue, the percentage fall in quantity is smaller than the percentage rise in price — demand is inelastic (|E| < 1). Distractors: A) unit elastic would leave total revenue unchanged. B) perfectly elastic demand would send revenue to zero after any price rise. D) perfectly inelastic is a special case; "inelastic" is the general answer. E) if demand were elastic, a price rise would lower total revenue. Fix: Price up + revenue up = inelastic; price up + revenue down = elastic. [Analyze]

26. D) a prisoner's dilemma in which advertising is a dominant strategy. Each firm's best move is to advertise no matter what the rival does (dominant strategy), yet the joint outcome is worse than mutual non-advertising — the classic dilemma. Distractors: A) this is strategic oligopoly interaction, not price-taking competition. B) two interacting firms are not a natural monopoly. C) the incentive to advertise is exactly what breaks cooperation. E) the equilibrium is inefficient for the firms, not allocatively efficient. Fix: Dominant strategy for each + worse joint result = prisoner's dilemma. [Analyze]

27. B) Ana bakes bread and Ben sews shirts. Ana's opportunity cost of a shirt is 2 loaves; Ben's is 1 loaf — Ben has the comparative advantage in shirts. Conversely Ana's cost of a loaf is ½ shirt versus Ben's 1 shirt, so Ana has the comparative advantage in bread. Each specializes where its opportunity cost is lower. Distractors: A) reverses the comparative advantages. C) absolute advantage in both does not mean Ana should make both — comparative advantage governs. D) specialization along comparative advantage yields gains, so "neither" is wrong. E) Ben is worse at both in absolute terms and cannot gain by making both. Fix: Compare opportunity costs, not absolute output; each party specializes where its opportunity cost is lowest. [Apply]

28. A) $10. Marginal cost = change in total cost / change in output = ($340 − $300) / (24 − 20) = $40 / 4 = $10 per unit. Distractors: B) $40 is the total cost increase, not the per-unit MC. C) $4 is the output increase alone. D) $14.17 is roughly average total cost ($340/24), not marginal. E) $15 has no basis in the numbers. Fix: MC = ΔTC / ΔQ — always divide the cost change by the number of extra units. [Apply]

29. E) labor demand to increase, because the marginal revenue product of labor rises. MRP = MPL × output price; a higher output price raises MRP at every level, shifting the labor demand curve rightward. Distractors: A) the shock raises labor demand, not supply. B) higher labor demand raises the wage, not lowers it. C) a change in the output price shifts the whole labor demand curve, not a movement along it. D) more output value means firms want more workers, not fewer. Fix: Output price ↑ → MRP ↑ → labor demand shifts right (derived demand). [Analyze]

30. C) 1.0. %ΔQ = −20/100 = −20%; %ΔP = +2/10 = +20%. Elasticity = |−20% / 20%| = 1.0 (unit elastic over this range). Distractors: A) 0.5 halves the quantity change. B) 2.0 inverts the ratio. D) 0.2 misplaces a decimal. E) 5.0 also inverts and mis-scales. Fix: Price elasticity = |%ΔQ ÷ %ΔP|; compute each percentage from the stated base, then divide. [Apply]

31. D) buy more of good X and less of good Y. When MUx/Px > MUy/Py, the last dollar buys more utility in X, so shifting spending toward X (and away from Y) raises total utility until the ratios equalize. Distractors: A) buying less of both wastes budget that could raise utility. B) shifting toward Y goes the wrong way. C) the bundle is not yet optimal — the ratios are unequal. E) buying more of both violates the fixed budget. Fix: Reallocate toward the good with the higher MU per dollar until MU/P is equal across goods. [Analyze]

32. B) prevent resale (arbitrage) between the buyers charged different prices. Price discrimination requires market power and the ability to stop low-price buyers from reselling to high-price buyers, which would otherwise undo the scheme. Distractors: A) perfectly elastic demand leaves no room to set different prices. C) constant marginal cost is not a requirement. D) perfect competitors are price takers and cannot discriminate. E) charging one price is the opposite of discrimination. Fix: Price discrimination needs market power + segmentable buyers + no arbitrage (resale blocked). [Understand]

33. A) supported by the Coase theorem — with low transaction costs, private bargaining internalizes the externality. Coase showed that if property rights are clear and bargaining is costless, parties negotiate to the efficient outcome regardless of who holds the right. Distractors: B) externalities can also be solved by bargaining, not only taxes. C) no subsidy is required for the Coase result. D) free-riding is a public-good problem, not this bargaining case. E) the theorem applies to externalities generally, not only public goods. Fix: Coase theorem: clear property rights + low transaction costs → private bargaining reaches efficiency, whoever owns the right. [Evaluate]

34. E) create a surplus of labor (unemployment), since quantity supplied exceeds quantity demanded. A minimum wage above equilibrium is a binding price floor in the labor market: more workers want jobs than firms will hire, and the gap is unemployment. Distractors: A) a binding floor lowers employment, not raises it. B) an above-equilibrium floor does bind and reduces employment. C) the wage is pushed above equilibrium, not below. D) the quantity of labor demanded falls at the higher wage. Fix: Minimum wage above equilibrium = binding floor = labor surplus = unemployment; quantity traded falls to the short (demand) side. [Analyze]

35. C) increase, as buyers stock up now. An expected future price increase raises current demand as consumers buy before the rise — the whole current demand curve shifts right. Distractors: A) waiting would apply if buyers expected prices to fall. B) expectations are a demand determinant, so there is an effect. D) buyer expectations shift demand, not supply. E) an expectations change shifts the curve, not a movement along it. Fix: Expecting a higher future price shifts current demand right (buy now); expecting a lower price shifts it left. [Apply]

36. D) $600. Economic profit = (P − ATC) × Q = ($20 − $14) × 100 = $6 × 100 = $600. Distractors: A) $2,000 uses P × Q minus nothing meaningful, or misreads the numbers. B) $1,400 is total cost (14 × 100), not profit. C) $200 misdivides. E) $340 has no basis. Fix: Profit = (price − average total cost) × quantity; use ATC, never MC, in the profit formula. [Apply]

37. B) a delivery truck used by a business. In economics, capital means physical goods (tools, equipment, buildings) used to produce other goods — a delivery truck qualifies. Distractors: A) savings are financial capital, not an economic factor of production. C) a bond is a financial asset. D) stock is financial ownership, not physical capital. E) wages are payments to labor, not capital itself. Fix: Economic capital = produced physical inputs (machines, tools, buildings), not money or financial assets. [Understand]

38. A) economies of scale. When long-run average total cost falls as output rises (all inputs variable), the firm enjoys economies of scale. Distractors: B) diminishing marginal returns is a short-run idea with a fixed input. C) diseconomies of scale would raise LRATC, not lower it. D) constant returns to scale would leave LRATC flat. E) rising marginal cost does not by itself lower average cost. Fix: LRATC falling with output = economies of scale; flat = constant; rising = diseconomies. [Understand]

39. E) incorrect, because profit is a transfer from consumers to the firm, whereas the efficiency loss is the deadweight-loss triangle from reduced output. Monopoly profit is a redistribution of surplus, not destroyed value; the true social harm is the deadweight loss on units between the monopoly and efficient quantities. Distractors: A) profit (a rectangle transfer) is not the deadweight loss (a triangle of lost surplus). B) profit and lost consumer surplus are different areas. C) monopolies can and often do earn profit. D) total revenue is not the measure of harm. Fix: Distinguish transfer (profit rectangle — someone gets it) from deadweight loss (triangle — no one gets it). [Evaluate]

40. C) complements. A negative cross-price elasticity means the two goods move opposite ways — a higher price of one lowers quantity demanded of the other — the signature of complements. Distractors: A) substitutes have a positive cross-price elasticity. B) unrelated goods have a cross-price elasticity near zero. D) inferior refers to income elasticity, not cross-price. E) normal likewise refers to income elasticity. Fix: Cross-price elasticity: positive = substitutes, negative = complements, ~0 = unrelated. [Understand]

41. B) the marginal external cost at the efficient quantity. A Pigouvian tax equal to the marginal external cost forces producers to internalize the externality, aligning private with social cost at the efficient output. Distractors: A) total cost of production is unrelated to the external harm. C) average cost is not the corrective amount. D) the tax targets the external cost, not lost consumer surplus. E) a well-set corrective tax raises efficiency, not lowers it. Fix: Optimal externality tax = marginal external cost at the efficient quantity, so MPC + tax = MSC. [Analyze]

42. D) marginal cost equals price, which also equals marginal revenue. A price taker maximizes profit at the output where P = MR = MC on the upward-sloping part of MC. Distractors: A) P = ATC is the zero-profit condition, not the profit-max quantity rule. B) "price at its maximum" is meaningless for a price taker. C) maximizing the MR − MC gap is not the rule; produce until they are equal. E) minimizing AVC is the shutdown margin, not profit maximization. Fix: Competitive profit max: produce where P = MC (= MR). [Understand]

43. A) positive but decreasing. If total utility rises but by ever-smaller increments, each added slice still adds utility (positive MU) but less than the last (diminishing MU). Distractors: B) MU is positive while total utility is still rising, not negative. C) constant MU would add equal amounts, giving a straight-line total utility. D) increasing MU would make total utility rise faster, not slower. E) zero MU would leave total utility flat. Fix: Total utility rising at a decreasing rate ⇔ marginal utility positive but falling. [Apply]

44. E) the government ought to raise the minimum wage to help workers. A normative statement expresses a value judgment about what ought to be — "ought to" is the tell. Distractors: A) a testable cause-effect claim — positive. B) a factual measurement — positive. C) a testable prediction — positive. D) a factual historical claim — positive. Fix: Normative = "should/ought" value claim; positive = testable "is/will" claim about facts. [Evaluate]

45. C) price equals marginal cost, so the value of the last unit to buyers equals its cost of production. Allocative efficiency requires P = MC; in long-run competition this holds, so exactly the right quantity is produced. Distractors: A) long-run competitive profit is zero, not large. B) P exceeding MC is the inefficient (monopoly) case. D) firms produce at minimum ATC, not below it. E) restricting output to raise price is monopoly behavior, the opposite of efficiency. Fix: Allocative efficiency ⇔ P = MC; competition delivers it, monopoly (P > MC) does not. [Analyze]

46. B) increase supply, lowering the price and raising the quantity. Better technology lowers production costs, shifting the supply curve right — price falls and equilibrium quantity rises. Distractors: A) technology increases supply, not decreases it. C) technology shifts supply, not demand. D) demand is unaffected by a production technology change. E) a cost change shifts the whole supply curve, not a movement along it. Fix: Improved technology → supply shifts right → lower price, higher quantity. [Apply]

47. D) the minimum point of the average total cost curve. Marginal cost cuts through ATC exactly at ATC's minimum: while MC < ATC, ATC falls; once MC > ATC, ATC rises. Distractors: A) MC crosses at ATC's minimum, not maximum. B) the crossing is at ATC's minimum, not MC's minimum. C) MC equals ATC only at that single point. E) AVC being zero is unrelated to the crossing. Fix: MC intersects ATC (and AVC) at that curve's minimum point — the marginal-average rule. [Analyze]

48. A) resources are unemployed or being used inefficiently. Points inside the PPF are attainable but wasteful — some resources are idle or misallocated, so more of both goods could be produced. Distractors: B) inside points are attainable; outside points are unattainable. C) opportunity cost is not zero simply because output is inside the frontier. D) allocative efficiency requires being on the frontier at the right mix. E) growth shifts the whole curve outward, not a point inside it. Fix: Inside the PPF = unemployment/inefficiency; on the PPF = productive efficiency; outside = currently unattainable. [Analyze]

49. E) $40. Marginal revenue product = marginal product × output price = 8 units × $5 = $40; that is the maximum wage the firm would pay for this worker. Distractors: A) $5 is the output price alone. B) $8 is the physical marginal product alone. C) $13 adds price and product with no economic meaning. D) $1.60 divides instead of multiplies. Fix: MRP = marginal product × price; a firm hires while MRP ≥ wage. [Apply]

50. C) the tragedy of the commons — a rival but nonexcludable resource being overused. An unowned fishery is rival (each fish caught leaves fewer for others) but nonexcludable (no one can be barred), so users overexploit it. Distractors: A) a public good is nonrival; fish are rival. B) overfishing is overuse of a common resource, not a positive externality. D) natural monopoly is a cost-structure idea, unrelated. E) overuse is inefficient, not efficient. Fix: Rival + nonexcludable = common resource → tragedy of the commons (overuse). [Understand]

51. B) perfectly inelastic. Zero response of quantity to any price change means a vertical demand curve — perfectly inelastic (elasticity = 0). Distractors: A) unit elastic means a 1-for-1 percentage response, not zero. C) perfectly elastic is the opposite extreme (horizontal). D) relatively elastic means quantity responds a lot. E) income elastic refers to income, not price. Fix: Quantity utterly unresponsive to price = perfectly inelastic (vertical) demand; elasticity = 0. [Understand]

52. D) cheat by secretly increasing output to sell more at the high cartel price. Each cartel member gains by quietly expanding output at the elevated price, which is exactly why cartels are unstable and tend to break down. Distractors: A) cutting output further sacrifices profit at the high price. B) exiting forgoes the cartel's profits. C) raising price above the cartel level would lose the member all its sales. E) merging is a structural change, not the private incentive each firm faces. Fix: Cartels are unstable because each member's dominant temptation is to cheat by overproducing at the agreed high price. [Analyze]

53. A) a sunk cost that is irrelevant to the decision. Money already spent and unrecoverable is sunk; rational decisions weigh only future marginal costs and benefits, ignoring sunk costs. Distractors: B) it is not a variable cost of the go-forward decision. C) sunk money is not an opportunity cost — it is gone either way. D) it is a past cost, not a marginal benefit. E) "not wasting" past spending is the sunk-cost fallacy. Fix: Ignore sunk costs; base decisions on future marginal benefit vs. marginal cost only. [Apply]

54. E) the additional output produced by hiring one more worker. Marginal product of labor is the extra output from one additional unit of labor, holding other inputs fixed. Distractors: A) output ÷ workers is average product, not marginal. B) the change in total cost from a worker is marginal factor cost. C) output per unit of capital is a different productivity measure. D) wage ÷ output has no standard meaning here. Fix: MPL = ΔTotal output ÷ Δlabor — the extra output from one more worker. [Remember]

55. C) to sell an additional unit the firm must lower the price on all units it sells. A single-price monopolist faces downward-sloping demand, so selling one more unit means cutting price on every unit — MR is the new price minus the revenue lost on earlier units, hence MR < P. Distractors: A) a horizontal demand curve describes a price taker, where MR = P. B) rising marginal cost is a cost-side fact, not the reason MR < P. D) profit maximization is the objective, not why MR sits below price. E) barrier costs affect profit, not the MR–price relationship. Fix: Downward-sloping demand + one price for all units → MR < P after the first unit. [Analyze]

56. B) a shortage, because quantity demanded exceeds quantity supplied. A binding ceiling sits below equilibrium: buyers want more than sellers offer, so a shortage appears and quantity traded falls to the amount supplied. Distractors: A) surpluses come from binding floors, not ceilings. C) the quantity traded falls, it does not rise. D) a binding ceiling is below equilibrium, so it does have an effect. E) a price control does not shift supply; it moves along it. Fix: Binding ceiling (below equilibrium) → shortage; binding floor (above equilibrium) → surplus. [Understand]

57. D) an increase in the consumer's income, with prices unchanged. A parallel outward shift of the budget line means more of both goods is affordable with the same relative prices — a rise in income. Distractors: A) a price change would rotate the budget line, not shift it parallel. B) tastes affect indifference curves, not the budget line. C) a single price change rotates the line. E) lower income shifts it inward, not outward. Fix: Income change → parallel budget-line shift; a single price change → rotation (pivot). [Analyze]

58. A) less than the output at minimum average total cost, operating with excess capacity. Because demand slopes down, a monopolistic competitor's zero-profit tangency lies on the falling part of ATC, so it produces below minimum-ATC output — the excess-capacity result. Distractors: B) only perfect competition reaches minimum ATC in the long run. C) it produces less than the efficient scale, not more. D) P > MC here, they are not equal. E) long-run economic profit is zero, competed away by entry. Fix: Monopolistic competition → excess capacity: output below minimum-ATC scale, P > MC, zero long-run profit. [Analyze]

59. E) nonexcludable, so consumers can free-ride and private firms cannot capture payment. Defense benefits everyone whether or not they pay, so private sellers cannot exclude non-payers and cannot cover costs — the free-rider problem justifies public provision. Distractors: A) defense is nonrival and nonexcludable, not rival and excludable. B) no law forbids private provision; the market simply fails. C) diminishing marginal utility is unrelated to why markets under-provide it. D) defense is a public good, not a common (rival) resource. Fix: Public goods fail in markets because nonexcludability enables free-riding, so private firms cannot capture payment. [Analyze]

60. C) depends on the demand for the output that labor helps produce. Labor demand is "derived" because firms hire workers only for the value of what those workers produce; when product demand rises, so does labor demand. Distractors: A) unions may affect supply/wages but do not define derived demand. B) labor demand slopes down, not up. D) the minimum wage is a price floor, not the source of derived demand. E) productivity is central to labor demand, not unrelated. Fix: "Derived demand" = demand for an input driven by demand for the output it makes. [Understand]

61. B) −$20,000. Economic profit = revenue − explicit costs − implicit costs = $200,000 − $120,000 − $100,000 = −$20,000. Distractors: A) $80,000 is accounting profit (it omits the $100,000 implicit cost). C) $200,000 is revenue alone. D) $100,000 is the implicit cost alone. E) $20,000 drops the negative sign. Fix: Economic profit subtracts implicit (opportunity) costs too; accounting profit only subtracts explicit costs. [Apply]

62. D) economies of scale are so extensive that one firm can serve the whole market at lower average cost than two or more firms could. A natural monopoly arises purely from a cost structure in which a single large producer has lower average cost than several smaller ones. Distractors: A) a patent creates a legal monopoly, not a natural one. B) resource control is a different barrier to entry. C) network effects are a distinct source of market power. E) collusion creates a cartel, not a natural monopoly. Fix: Natural monopoly = one firm supplies the market at lower average cost because of large, persistent economies of scale. [Understand]

63. A) marginal benefit equals marginal cost. Rational optimization means expanding an activity while marginal benefit exceeds marginal cost and stopping exactly where MB = MC — the net-benefit-maximizing point. Distractors: B) chasing total benefit while ignoring cost overshoots the optimum. C) marginal cost rarely reaches zero and is not the stopping rule. D) averages are not the correct decision margin. E) zero total cost is neither achievable nor the goal. Fix: Optimize on the margin: do more until MB = MC. [Understand]

64. E) regressive. A tax that takes a larger share of income from lower-income households than from higher-income ones is regressive by definition. Distractors: A) progressive is the opposite — a larger share from higher incomes. B) proportional takes the same share from all. C) a lump-sum tax is a fixed dollar amount, described differently. D) an excise tax is defined by its base (a specific good), not its income incidence. Fix: Progressive = larger share as income rises; proportional = same share; regressive = larger share as income falls. [Understand]

65. C) a surplus, because quantity supplied exceeds quantity demanded. A price floor above equilibrium binds: sellers offer more than buyers want, creating a surplus, and quantity traded falls to the amount demanded. Distractors: A) shortages come from binding ceilings, not floors. B) a floor holds the price up, above equilibrium. D) a floor above equilibrium is binding, not a no-effect case. E) quantity traded falls, it does not rise. Fix: Binding floor (above equilibrium) → surplus; quantity traded falls to the short (demand) side. [Apply]

66. B) issue a limited number of tradable emission permits, letting firms that can abate cheaply sell to those who cannot. A cap-and-trade market equalizes marginal abatement costs across firms, hitting the emissions target at the lowest total cost. Distractors: A) uniform mandatory cuts ignore differing abatement costs and cost more overall. C) an immediate total ban is drastically costly and usually infeasible. D) equal subsidies do not target the cheapest abatement. E) pollution externalities do not self-correct. Fix: Tradable permits minimize total abatement cost by letting low-cost abaters cut most and sell permits to high-cost abaters. [Evaluate]

67. D) falls continually, as a fixed total is spread over more units. Average fixed cost = fixed cost ÷ quantity; since the numerator is constant, AFC declines steadily as output rises. Distractors: A) AFC falls, it does not rise. B) AFC is not constant — only total fixed cost is. C) AFC declines monotonically, never U-shaped. E) AFC equals MC only by coincidence, not as a rule. Fix: AFC = FC/Q always falls as Q rises ("spreading the overhead"). [Apply]

68. A) greater than marginal cost, which signals allocative inefficiency. A monopolist produces where MR = MC, then charges the higher demand-curve price, so P > MC — too little is produced relative to the efficient P = MC point. Distractors: B) P = MC is the competitive/efficient outcome, not monopoly. C) P is above MC, not below. D) the monopolist sets MR = MC, but price is read off demand above MR, so P > MR = MC. E) P equals ATC only by coincidence, not as a rule. Fix: Monopoly: MR = MC sets quantity, but P (on demand) > MC → allocative inefficiency. [Analyze]

69. E) additional human capital raises their marginal product, and therefore their marginal revenue product. More education builds human capital, making workers more productive; higher marginal product raises their MRP and thus the wage firms will pay. Distractors: A) no law ties pay to education. B) education does not shrink total labor supply. C) unions are not the general explanation for the education wage premium. D) higher income brackets are a result of higher wages, not the cause. Fix: Education → more human capital → higher marginal product → higher MRP → higher wage. [Analyze]

70. C) constant, as shown by the constant slope of the line. A straight-line PPF has a constant slope, so each extra gun always costs the same amount of butter — constant opportunity cost. Distractors: A) increasing opportunity cost gives a bowed-out curve, not a straight line. B) opportunity cost is positive along any downward-sloping PPF. D) the trade-off does not shrink along a straight line. E) the cost is a rate of exchange, not the total stock of butter. Fix: Straight-line PPF = constant opportunity cost (constant slope); bowed-out = increasing opportunity cost. [Apply]

71. B) close substitutes are readily available. When good substitutes exist, buyers switch away easily after a price rise, making quantity demanded very responsive — more elastic. Distractors: A) necessities are less elastic. C) a tiny budget share makes demand less elastic. D) short time horizons make demand less elastic (less time to adjust). E) broadly defined goods have fewer substitutes and are less elastic. Fix: More elastic when: many substitutes, luxury, large budget share, longer time horizon, narrowly defined good. [Analyze]

72. D) the market price. A perfectly competitive firm is a price taker, so each extra unit sells at the going price — MR = P (and its demand curve is horizontal at P). Distractors: A) MR relates to revenue, not average total cost. B) MR = P at every output, not only at shutdown. C) the slope of total cost is marginal cost, not MR. E) MR equals the price, which is positive, not zero. Fix: Perfect competition: MR = P (the firm's horizontal demand curve). [Understand]

73. A) adverse selection arising from asymmetric information. When sellers know quality but buyers do not, buyers offer only an average price; good-car owners withdraw, leaving mostly lemons — adverse selection before the transaction. Distractors: B) this is an information problem, not a spillover benefit. C) used cars are private goods, not public goods. D) economies of scale concern costs, not information. E) no price control is involved. Fix: Hidden quality known to one side before a deal = asymmetric information → adverse selection (the "lemons" problem). [Analyze]

74. E) occur in the short run, when a variable input is added to at least one fixed input. Diminishing marginal returns are a short-run effect with a fixed input; diseconomies of scale are a long-run effect when all inputs grow. Distractors: A) diminishing returns are short-run, not long-run. B) rising average cost as the whole firm grows describes diseconomies of scale. C) diminishing returns apply when one input is fixed, not all variable. D) the two concepts are distinct, not synonyms. Fix: Diminishing marginal returns = short run (fixed input); diseconomies of scale = long run (all inputs vary). [Analyze]

75. C) generally correct, because competition expands output to where price equals marginal cost, eliminating the monopoly deadweight loss. Replacing a single-price monopoly with competition (same costs) raises output to the P = MC level, recovering the deadweight-loss triangle and increasing total surplus. Distractors: A) monopoly reduces total surplus relative to competition. B) long-run competition has no deadweight loss. D) the surplus gain holds whether or not the monopoly was profitable. E) surplus is precisely what lets us compare the two structures. Fix: Competition (P = MC) yields more total surplus than single-price monopoly (P > MC) with the same costs. [Evaluate]

76. B) at its maximum. For a free good, total utility rises as long as marginal utility is positive and falls once it turns negative, so total utility peaks exactly where marginal utility = 0. Distractors: A) total utility is at its highest, not zero. C) total utility stops rising at MU = 0, it is not still climbing. D) total utility is maximal, not negative (MU would have to be negative for that). E) it is a maximum, not a minimum. Fix: Total utility is maximized where marginal utility = 0 (the peak of the total-utility curve). [Analyze]

77. D) lower the equilibrium wage and raise the quantity of labor employed. A rightward shift of labor supply along a fixed, downward-sloping labor demand curve lowers the wage and increases the number of workers hired. Distractors: A) more supply lowers the wage, it does not raise it. B) employment rises as the market moves down the demand curve. C) with more supply and unchanged demand, the wage must fall. E) a supply shift does not move the demand curve. Fix: Labor supply ↑ (demand fixed) → lower wage, higher employment (movement down labor demand). [Analyze]

78. A) the tax will create a large deadweight loss and raise relatively little revenue, because elastic curves make quantity fall sharply. When both curves are elastic, a tax causes a big drop in quantity traded, so the deadweight-loss triangle is large and the taxed quantity (and thus revenue) is small. Distractors: B) elastic markets are exactly where taxes are least efficient (biggest DWL). C) elastic demand pushes the burden onto sellers, not entirely onto buyers. D) any tax on a downward-sloping/upward-sloping pair creates some deadweight loss. E) revenue and deadweight loss are different areas and need not be equal. Fix: Elastic supply and demand → large quantity drop → large deadweight loss and low revenue; inelastic markets are the efficient tax base. [Evaluate]

79. E) keep producing where price equals marginal cost, because revenue covers all variable cost plus part of fixed cost. With P above AVC, operating loses less than shutting down (which would still owe all fixed cost), so the firm produces at P = MC and minimizes its loss in the short run. Distractors: A) shutting down leaves the firm owing all fixed cost — a bigger loss. B) exit is a long-run decision, not the short-run response. C) a price taker cannot raise its price. D) the firm produces where P = MC, not where P = ATC. Fix: Short run: if P ≥ AVC, keep producing at P = MC to cover variable cost plus part of fixed cost; shut down only if P < AVC. [Analyze]

80. C) for whom to produce — who receives the output. Every economy must decide what goods to make, how to make them, and for whom — how output is distributed among people. Distractors: A) scarcity cannot be eliminated; it is the permanent condition economics addresses. B) zero prices do not resolve the three basic questions. D) opportunity cost is inherent in scarcity and cannot be abolished. E) equal incomes are one possible distribution choice, not the general "for whom" question. Fix: The three basic economic questions: what to produce, how to produce, and for whom to produce. [Understand]

Scaled Score Estimator

CLEP reports scores on a 20–80 scale, with ACE-recommended credit at 50. The exact conversion is proprietary and varies slightly by form; the table below uses a transparent linear approximation, scaled = 20 + 0.75 × (raw score), for self-assessment only. On this 80-item mock, roughly 40 correct (50%) maps to the credit line of 50.

Disclaimer: CLEP's official raw-to-scaled conversion is proprietary and not published; this table is an approximation for practice only and should not be read as a guaranteed score.