Questions: Consumer Surplus, Producer Surplus, and Deadweight Loss
5 questions to test your understanding
Score: 0 / 5
Question 1 Multiple Choice
A government imposes an excise tax. Consumer surplus falls by $300M, producer surplus falls by $400M, and the government collects $500M in revenue. What is the deadweight loss?
A$200M — the surplus losses ($700M) minus the tax revenue transferred to government ($500M)
B$700M — the total reduction in consumer and producer surplus
C$500M — deadweight loss equals the revenue the government collected
D$0 — taxes just redistribute surplus from private actors to government without destroying any
Tax revenue is a transfer, not a loss — it leaves consumers and producers but arrives at the government, which can spend it. Only the portion of surplus loss that goes to nobody is deadweight loss. DWL = (CS loss + PS loss) − tax revenue = ($300M + $400M) − $500M = $200M. This $200M represents the value of transactions that would have been mutually beneficial but didn't happen once the tax wedge was inserted. Option D is the classic misconception: it ignores that quantity falls, destroying trades.
Question 2 Multiple Choice
Two markets have identical demand curves but different supply elasticities: Market A has highly elastic supply, Market B has highly inelastic supply. A $10 excise tax is applied to both. Which market has larger deadweight loss?
AMarket A — elastic supply means quantity falls more in response to the tax wedge, making the DWL triangle larger
BMarket B — inelastic supply means producers absorb more of the tax, increasing total burden
CBoth markets have identical DWL because the tax size ($10) is the same in both
DNeither market has any DWL — DWL only arises from price controls, not taxes
DWL is the area of the triangle formed between the old and new quantities — its size depends on how much quantity falls. With elastic supply, a tax causes a larger quantity reduction (producers easily exit or cut back), producing a wider triangle. With inelastic supply, quantity barely changes despite the tax, producing only a small DWL triangle. The same logic applies to demand elasticity. This is why sin taxes (on addictive goods with inelastic demand) raise revenue with relatively little DWL — the quantity barely falls.
Question 3 True / False
Tax revenue collected from an excise tax represents a deadweight loss to society, because it was taken from consumers and producers.
TTrue
FFalse
Answer: False
Tax revenue is a transfer, not a deadweight loss. It leaves consumers and producers but arrives at the government, which can use it for public goods, infrastructure, or redistribution — all of which may produce value. Deadweight loss is the portion of surplus that disappears entirely: it goes to no one. DWL represents trades that were mutually beneficial but no longer occur after the tax wedge. Revenue is always shown as a rectangle in the supply-demand diagram; DWL is the remaining triangle of lost trades beyond that rectangle.
Question 4 True / False
A price ceiling set below equilibrium creates deadweight loss because some mutually beneficial trades — where a buyer's willingness to pay exceeds a seller's minimum acceptable price — no longer occur.
TTrue
FFalse
Answer: True
At the artificially low ceiling price, some sellers are no longer willing to supply (their minimum acceptable price exceeds the ceiling), so quantity supplied falls below the competitive equilibrium quantity. The buyers who were willing to pay more than the sellers' costs but can't find a seller at the ceiling price represent foregone gains from trade — the deadweight loss. This geometry is identical to the DWL triangle from a tax, just with a different mechanism causing the quantity restriction.
Question 5 Short Answer
Explain why deadweight loss is sometimes described as 'lost surplus that benefits no one.' How does this distinguish DWL from tax revenue?
Think about your answer, then reveal below.
Model answer: Tax revenue is taken from consumers/producers but given to the government — it's a redistribution. DWL is the value of trades that would have happened at equilibrium but don't happen once a policy intervenes. No one receives this value: not consumers, not producers, not the government. It vanishes from the economy entirely because potential buyers and sellers who would have transacted at the equilibrium price can no longer do so at the distorted price.
The geometry makes this vivid: draw the supply-demand graph with a tax. The tax rectangle (height = tax rate, width = quantity traded) is revenue — a transfer. The DWL triangle sits to the right of the new quantity and to the left of the old equilibrium quantity, bounded by the demand curve above and supply curve below. This triangle represents deals that were worth making (demand ≥ supply) but don't happen because the after-tax cost to buyers exceeds after-tax revenue to sellers. No policy actor captures this triangle — it is pure destruction of potential value.