You would have paid up to $50 for a jacket; it cost $30. You quietly pocketed $20 of value — consumer surplus. The seller who would have accepted $18 pocketed $12 of producer surplus. Markets create these gains on every trade, and this lesson is about measuring them — and measuring what is destroyed when governments cap prices, prop them up, or tax transactions. Graph-area questions like these are among the most point-dense on the CLEP exam.
[GRAPH: Supply and demand crossing at P = $6, Q = 100. Triangle between demand curve and the P line from Q = 0 to Q = 100 shaded and labeled "CS". Triangle between the P line and supply curve shaded and labeled "PS". Demand intercept $10; supply intercept $2.]
With linear curves these are triangles: area = ½ × base × height. In the graph above: CS = ½ × 100 × (10 − 6) = $200; PS = ½ × 100 × (6 − 2) = $200; total surplus = $400. The heights come from the intercepts: demand chokes off at $10, supply starts at $2.
At competitive equilibrium, total surplus is maximized — this is allocative efficiency: every unit for which willingness to pay ≥ marginal cost gets produced (up to where P = MC), and no unit for which cost exceeds value does.
Deadweight loss (DWL) is total surplus destroyed when the market quantity is not the efficient quantity — either trades that would have created value never happen (underproduction) or trades that destroy value happen (overproduction). Graphically, DWL is the triangle between the demand and supply curves, spanning from the actual quantity to Q*.
A price ceiling is a legal maximum price (rent control, anti-gouging laws). It matters only if set below equilibrium — a "binding" ceiling.
[GRAPH: Supply and demand, equilibrium at P = $6, Q = 100. Horizontal line at Pc = $4 below equilibrium labeled "price ceiling". At $4: Qs = 60, Qd = 140; horizontal gap labeled "shortage = 80". DWL triangle between the curves from Q = 60 to Q = 100 shaded.]
Consequences of a binding ceiling: - Shortage (Qd > Qs); quantity traded falls to Qs — the short side of the market rules - Deadweight loss from the lost trades - Non-price rationing: waiting lists, favoritism, quality deterioration, black markets (all familiar from rent-controlled housing markets) - CS may rise or fall; PS unambiguously falls - A ceiling set above equilibrium is nonbinding — no effect at all
A price floor is a legal minimum price (minimum wage, agricultural price supports). It matters only if set above equilibrium.
[GRAPH: Supply and demand, equilibrium at P = $6, Q = 100. Horizontal line at Pf = $8 above equilibrium labeled "price floor". At $8: Qd = 60, Qs = 140; gap labeled "surplus = 80". DWL triangle from Q = 60 to Q = 100 shaded.]
Consequences of a binding floor: - Surplus (Qs > Qd); quantity traded falls to Qd - Deadweight loss; sellers compete in non-price ways; the government may buy the surplus (farm programs) - In the labor market: a binding minimum wage → surplus of labor = unemployment (more hours offered than hired)
Quantity traded always falls under a binding control — whichever of Qd and Qs is smaller governs.
A per-unit (excise) tax of $T collected from sellers shifts the supply curve up/left by exactly $T (each unit now needs $T more to be worth supplying).
[GRAPH: Demand and original supply S₁ at equilibrium ($6, 100). New curve S₂ parallel, vertically $2 above S₁. New intersection with D at Pb = $7.20, Q = 80. Price sellers keep: Ps = Pb − 2 = $5.20. Bracket showing the $2 tax wedge between $7.20 and $5.20 at Q = 80. Government revenue rectangle = 2 × 80. DWL triangle between the curves from Q = 80 to Q = 100.]
Outcomes: - Buyers pay Pb (above the old P); sellers keep Ps = Pb − T - Quantity falls → DWL = ½ × ΔQ × T with linear curves (the tax blocks mutually beneficial trades) - Government revenue = T × new Q (a rectangle) - Tax incidence (who bears the burden) depends on relative elasticities, not on who legally pays: the more inelastic side bears more of the tax. Perfectly inelastic demand → buyers bear it all; perfectly elastic demand → sellers bear it all. - More elastic curves (on either side) → bigger quantity drop → bigger DWL*.
Burden check: buyer burden + seller burden must sum to government revenue. In the graph: buyers pay (7.20 − 6.00) × 80 = $96; sellers absorb (6.00 − 5.20) × 80 = $64; total $160 = 2 × 80 ✓. Use this to catch arithmetic slips.
A per-unit subsidy is the mirror image: supply shifts down/right by the subsidy, quantity rises past the efficient level, buyers pay less, sellers receive more, the government spends subsidy × Q, and there is DWL from overproduction — units whose resource cost exceeds their value to buyers get made anyway.
1. B — CS is the value buyers receive above what they pay: under the demand curve, above the price line, out to the quantity traded. - A: that area is producer surplus — the mirror image. - C: the full area between the curves at all quantities mixes surplus with regions where no trades occur. - D: below the price and above the axis is total expenditure (P × Q), not surplus. - E: above demand lies willingness to pay that no buyer has — an empty region. - Fix: CS lives under demand and above price; PS lives above supply and below price.
2. B — Allocative efficiency means maximum total surplus: every unit with willingness to pay ≥ marginal cost is produced, up to where P = MC. - A: maximizing CS alone would call for a price of zero, which destroys producer-side gains. - C: maximizing PS alone would call for restricting output and raising price — the monopoly direction. - D: government revenue is not part of the efficiency criterion in an untaxed competitive market. - E: affordability for every buyer is an equity idea, not the efficiency condition. - Fix: Efficiency = biggest combined pie (CS + PS), not the biggest slice for any one group.
3. B — $1,100 is below the $1,400 equilibrium, so the ceiling binds: Qd > Qs (shortage), quantity traded falls to Qs, and the lost rentals are deadweight loss. - A: ceilings create shortages; floors create surpluses. - C: total surplus falls, not rises — mutually beneficial rentals stop happening. - D: wrong on both counts — the gap is a shortage, and quantity traded falls. - E: reverses the binding rule; a ceiling below equilibrium is exactly the one that binds. - Fix: Ceiling below equilibrium → binds → shortage → quantity set by the short (supply) side → DWL.
4. D — CS = ½ × base × height = ½ × 8 × (20 − 12) = $32; the height runs from the $20 demand intercept down to the $12 price. - A ($64): forgets the ½ (or reports total surplus, since PS here is also $32). - B ($16): halves the correct answer by using the wrong height (the $4 supply intercept gap). - C ($256): multiplies price by quantity and more — an expenditure-style rectangle, not a surplus triangle. - E ($8): uses the quantity as the whole area, dropping the height. - Fix: Surplus triangles: base = quantity traded, height = intercept-to-price gap, then take half.
5. A — A floor binds only from above: set above the $14 equilibrium, employers demand fewer hours than workers offer, and employment falls. - B: below equilibrium the floor is nonbinding — the market wage already exceeds it. - C: at exactly equilibrium nothing changes; the market clears at $14 anyway. - D: enforcement can't make a nonbinding floor bind; the level relative to equilibrium is what matters. - E: the reservation wage is a supply-curve concept, not the binding condition for a floor. - Fix: Floors bind above equilibrium; ceilings bind below — draw the line on the correct side first.
6. A — If buyers don't reduce quantity at all (vertical demand), sellers can pass the entire $4 through: Pb rises by the full tax. - B: perfectly inelastic supply is the opposite case — sellers bear it all and the buyers' price doesn't rise. - C: perfectly elastic demand means buyers vanish at any higher price, so sellers absorb the whole tax. - D: equal elasticities split the burden roughly in half — buyers pay about $2 more, not $4. - E: legal incidence is irrelevant; collecting from buyers instead changes nothing about the economic burden. - Fix: The tax lands on whoever can't run — the more inelastic side bears more; perfectly inelastic bears all.
7. E — DWL = ½ × ΔQ × T = ½ × (200 − 150) × $6 = ½ × 50 × 6 = $150. - A ($300): forgets the ½ — that's the full rectangle on the lost units, not the triangle. - B ($900): computes government revenue (6 × 150) instead of DWL. - C ($1,200): taxes the original quantity (6 × 200), which is neither revenue nor DWL. - D ($75): halves twice. - Fix: DWL from a tax = ½ × (units lost) × (tax per unit) — triangle, so never skip the half.
8. D — Economic incidence follows relative elasticity: buyers of a staple can't cut back much, so the price they pay rises by most of the tax. - A: legal collection determines who mails the check, not who bears the burden. - B: burdens are equal only in the special case of equal elasticities. - C: the government receives revenue; it doesn't absorb the burden. - E: incidence is identical whether the tax is collected from buyers or sellers — the legal side is a distractor. - Fix: Ignore who legally pays; find the more inelastic curve — that side eats most of the tax.
9. E — With a binding ceiling, the short side rules: only 60,000 gallons are supplied and sold; the shortage is Qd − Qs = 140,000 − 60,000 = 80,000. - A: 140,000 is quantity demanded — stations won't supply that much at $3.00. - B: splitting the difference has no economic basis; nothing trades at the midpoint quantity. - C: quantity demanded exceeding quantity supplied is the definition of a shortage — it can't be absent. - D: right quantity sold, but the shortage is the full 80,000 gap, not 60,000. - Fix: Quantity traded = min(Qd, Qs); shortage = Qd − Qs at the controlled price.
10. C — Sellers kept $6.00 before and $5.20 after, so their burden is (6.00 − 5.20) × 80 = $64. Check: buyers bear (7.20 − 6.00) × 80 = $96, and 96 + 64 = $160 = $2 × 80 = revenue ✓. - A ($96): that's the buyers' share of the burden. - B ($160): total government revenue, not the sellers' portion. - D ($80): multiplies the quantity by $1 with no basis in the price changes. - E ($20): that's the deadweight loss (½ × 20 × 2), not a burden share. - Fix: Seller burden = (old price − price kept) × new Q; buyer + seller burdens must sum to revenue.
11. A — Subsidies push quantity past Q; on those extra units, marginal cost exceeds willingness to pay, so surplus is destroyed even though CS and PS both rise — the taxpayer cost exceeds the combined private gains. - B: subsidies increase quantity; shortages come from price ceilings. - C: a rightward supply shift raises consumer surplus (lower price, more quantity). - D: subsidy DWL exists for any ordinary elasticity; no special case is needed. - E: this is the exact misconception the question tests — any wedge that moves quantity away from Q, in either direction, creates DWL. - Fix: Overproduction destroys surplus too: DWL appears whenever quantity ≠ Q*, whether a tax pushed it down or a subsidy pushed it up.
12. C — $1,700 is above the $1,500 equilibrium, so the ceiling is nonbinding: the market stays at $1,500 and the equilibrium quantity. - A: a shortage requires a binding ceiling — one set below equilibrium. - B: surpluses come from binding floors, and no control binds here anyway. - D: a ceiling is a maximum, not a target — nothing pushes rents up to it. - E: with quantity unchanged at Q, no trades are lost and there is no DWL. - Fix:* Before analyzing any control, check the binding condition: ceiling below equilibrium, floor above — otherwise, no effect.
1. B — CS is the value buyers receive above what they pay: under the demand curve, above the price line, out to the quantity traded. - A: that area is producer surplus — the mirror image. - C: the full area between the curves at all quantities mixes surplus with regions where no trades occur. - D: below the price and above the axis is total expenditure (P × Q), not surplus. - E: above demand lies willingness to pay that no buyer has — an empty region. - Fix: CS lives under demand and above price; PS lives above supply and below price.
2. B — Allocative efficiency means maximum total surplus: every unit with willingness to pay ≥ marginal cost is produced, up to where P = MC. - A: maximizing CS alone would call for a price of zero, which destroys producer-side gains. - C: maximizing PS alone would call for restricting output and raising price — the monopoly direction. - D: government revenue is not part of the efficiency criterion in an untaxed competitive market. - E: affordability for every buyer is an equity idea, not the efficiency condition. - Fix: Efficiency = biggest combined pie (CS + PS), not the biggest slice for any one group.
3. B — $1,100 is below the $1,400 equilibrium, so the ceiling binds: Qd > Qs (shortage), quantity traded falls to Qs, and the lost rentals are deadweight loss. - A: ceilings create shortages; floors create surpluses. - C: total surplus falls, not rises — mutually beneficial rentals stop happening. - D: wrong on both counts — the gap is a shortage, and quantity traded falls. - E: reverses the binding rule; a ceiling below equilibrium is exactly the one that binds. - Fix: Ceiling below equilibrium → binds → shortage → quantity set by the short (supply) side → DWL.
4. D — CS = ½ × base × height = ½ × 8 × (20 − 12) = $32; the height runs from the $20 demand intercept down to the $12 price. - A ($64): forgets the ½ (or reports total surplus, since PS here is also $32). - B ($16): halves the correct answer by using the wrong height (the $4 supply intercept gap). - C ($256): multiplies price by quantity and more — an expenditure-style rectangle, not a surplus triangle. - E ($8): uses the quantity as the whole area, dropping the height. - Fix: Surplus triangles: base = quantity traded, height = intercept-to-price gap, then take half.
5. A — A floor binds only from above: set above the $14 equilibrium, employers demand fewer hours than workers offer, and employment falls. - B: below equilibrium the floor is nonbinding — the market wage already exceeds it. - C: at exactly equilibrium nothing changes; the market clears at $14 anyway. - D: enforcement can't make a nonbinding floor bind; the level relative to equilibrium is what matters. - E: the reservation wage is a supply-curve concept, not the binding condition for a floor. - Fix: Floors bind above equilibrium; ceilings bind below — draw the line on the correct side first.
6. A — If buyers don't reduce quantity at all (vertical demand), sellers can pass the entire $4 through: Pb rises by the full tax. - B: perfectly inelastic supply is the opposite case — sellers bear it all and the buyers' price doesn't rise. - C: perfectly elastic demand means buyers vanish at any higher price, so sellers absorb the whole tax. - D: equal elasticities split the burden roughly in half — buyers pay about $2 more, not $4. - E: legal incidence is irrelevant; collecting from buyers instead changes nothing about the economic burden. - Fix: The tax lands on whoever can't run — the more inelastic side bears more; perfectly inelastic bears all.
7. E — DWL = ½ × ΔQ × T = ½ × (200 − 150) × $6 = ½ × 50 × 6 = $150. - A ($300): forgets the ½ — that's the full rectangle on the lost units, not the triangle. - B ($900): computes government revenue (6 × 150) instead of DWL. - C ($1,200): taxes the original quantity (6 × 200), which is neither revenue nor DWL. - D ($75): halves twice. - Fix: DWL from a tax = ½ × (units lost) × (tax per unit) — triangle, so never skip the half.
8. D — Economic incidence follows relative elasticity: buyers of a staple can't cut back much, so the price they pay rises by most of the tax. - A: legal collection determines who mails the check, not who bears the burden. - B: burdens are equal only in the special case of equal elasticities. - C: the government receives revenue; it doesn't absorb the burden. - E: incidence is identical whether the tax is collected from buyers or sellers — the legal side is a distractor. - Fix: Ignore who legally pays; find the more inelastic curve — that side eats most of the tax.
9. E — With a binding ceiling, the short side rules: only 60,000 gallons are supplied and sold; the shortage is Qd − Qs = 140,000 − 60,000 = 80,000. - A: 140,000 is quantity demanded — stations won't supply that much at $3.00. - B: splitting the difference has no economic basis; nothing trades at the midpoint quantity. - C: quantity demanded exceeding quantity supplied is the definition of a shortage — it can't be absent. - D: right quantity sold, but the shortage is the full 80,000 gap, not 60,000. - Fix: Quantity traded = min(Qd, Qs); shortage = Qd − Qs at the controlled price.
10. C — Sellers kept $6.00 before and $5.20 after, so their burden is (6.00 − 5.20) × 80 = $64. Check: buyers bear (7.20 − 6.00) × 80 = $96, and 96 + 64 = $160 = $2 × 80 = revenue ✓. - A ($96): that's the buyers' share of the burden. - B ($160): total government revenue, not the sellers' portion. - D ($80): multiplies the quantity by $1 with no basis in the price changes. - E ($20): that's the deadweight loss (½ × 20 × 2), not a burden share. - Fix: Seller burden = (old price − price kept) × new Q; buyer + seller burdens must sum to revenue.
11. A — Subsidies push quantity past Q; on those extra units, marginal cost exceeds willingness to pay, so surplus is destroyed even though CS and PS both rise — the taxpayer cost exceeds the combined private gains. - B: subsidies increase quantity; shortages come from price ceilings. - C: a rightward supply shift raises consumer surplus (lower price, more quantity). - D: subsidy DWL exists for any ordinary elasticity; no special case is needed. - E: this is the exact misconception the question tests — any wedge that moves quantity away from Q, in either direction, creates DWL. - Fix: Overproduction destroys surplus too: DWL appears whenever quantity ≠ Q*, whether a tax pushed it down or a subsidy pushed it up.
12. C — $1,700 is above the $1,500 equilibrium, so the ceiling is nonbinding: the market stays at $1,500 and the equilibrium quantity. - A: a shortage requires a binding ceiling — one set below equilibrium. - B: surpluses come from binding floors, and no control binds here anyway. - D: a ceiling is a maximum, not a target — nothing pushes rents up to it. - E: with quantity unchanged at Q, no trades are lost and there is no DWL. - Fix:* Before analyzing any control, check the binding condition: ceiling below equilibrium, floor above — otherwise, no effect.