Supply: the supply curve and what shifts it
Grade 12 Social Studies Worksheet
Circle the best answer.
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Gasoline prices and miles driven, each April (EIA and Federal Highway Administration via FRED, read Nov 14, 2026). Columns: Month, Retail price of regular gasoline a gallon, Miles traveled by all vehicles. April 2019, $2.798, 273.4 billion; April 2020, $1.841, 167.6 billion; April 2021, $2.858, 252.2 billion; April 2022, $4.109, 258.0 billion. Miles traveled is a rough stand-in for gasoline used; compare the same month in different years. In our words: if one curve shifts, price and quantity moving the same way point to a demand shift, and moving in opposite directions to a supply shift.
Ari compares April 2019 with April 2020. Which shift does the evidence fit best?
- A rise in supply: price fell, and a supply rise is the usual cause of a lower price
- A fall in demand: price fell 34 percent and miles driven fell 39 percent, moving the same way
- A fall in supply: miles fell, and a supply fall is the usual cause of less driving
- A movement along demand: price fell, so buyers chose to drive less at the lower price
Bo compares April 2021 with April 2022, when price rose 44 percent and miles rose 2 percent. Which statement is best supported?
- Demand fell: price rose and miles driven hardly moved, so buyers held back this time around
- Neither curve shifted: the market moved along one curve to a higher price and a higher quantity
- Demand rose: price and miles moved together, though a small supply fall may be part of it
- Supply fell: a 44 percent price rise is the sign of a fall in supply and of nothing else on the card
Esme must pick the claim that the table cannot support. Which claim is it?
- The April 2022 price was about 44 percent above the April 2021 price
- Miles driven in April 2020 were about 39 percent below April 2019
- Miles driven in April 2022 were still below the April 2019 level
- The April 2022 price rise was caused by a fall in the supply of gasoline
A writer says demand for gasoline is elastic, since price fell 34 percent and miles fell 39 percent in April 2020. Jun tests it. What is the verdict?
- Shown: a ratio above 1 means that each price cut raised driving by a larger percent each time
- Not shown: elasticity of demand can be read just from changes in buyers' income
- Not shown: a demand fall moved the market along supply, so the 39 to 34 ratio is about supply
- Shown: miles fell by more than the price did, so buyers responded strongly to the lower price
A market before any shift (example figures, made up for practice)
Price per unit Quantity demanded Quantity supplied $20 350 150 $25 300 200 $30 250 250 $35 200 300 $40 150 350 $45 100 400 Equilibrium is $30 and 250. A shift moves the quantity at every price by the stated amount. Use the new quantities to find the price at which demand equals supply.
A cost shock cuts supply by 100 at each price. Kira finds the new equilibrium. Which pair is right?
- $40 and 250: the price rises $10 while the quantity stays at its old level
- $30 and 150: the price stays put and the quantity falls by the full 100 shift
- $35 and 200: the price rises $5 and the quantity falls 50
- $35 and 300: the price rises $5 and the quantity rises 50, as in a demand shift
Demand rises by 100 and supply rises by 100 at each price. Milo predicts the result. Which claim is best?
- Price must rise above $30, since demand rose by 100 and a demand rise lifts the price
- Quantity stays at 250, since the two shifts cancel each other out in the market
- Price must fall below $30, since supply rose by 100 and a supply rise lowers the price
- Quantity rises to 350; price stays at $30 here, but rises if demand outgrows supply
A reporter says the price moved from $30 to $35, so supply must have fallen. Noah tests it with the table. What is the best reply?
- Right: both explanations give the same quantity, so supply is the likelier cause
- Not necessarily: a demand rise of 100 also gives $35, with quantity up to 300, not 200
- Wrong: a price above $30 means demand rose, since buyers drive prices up in a market
- Right: a price of $35 shows supply fell, since sellers raise prices just when goods are scarce
Two markets, each with a $1.00 tax on every unit sold (example figures, made up for practice)
Market Elasticity of demand (size) Elasticity of supply Rice 0.5 1.5 Concert tickets 2.0 0.5 In our words, for a small tax: buyers bear a share equal to the elasticity of supply divided by the sum of the two elasticities, and sellers bear the rest. The side that responds less to price bears more. This holds whoever is billed.
Pia applies the rule to the rice market. Which statement about the $1.00 tax is best supported?
- Buyers bear 75 percent, about $0.75: 1.5 divided by (1.5 + 0.5)
- Buyers bear 25 percent, about $0.25: 0.5 divided by (1.5 + 0.5), the demand share
- Each side bears half, about $0.50, because the tax is $1.00 on each unit sold
- Sellers bear 75 percent, about $0.75, because the law bills the sellers of rice
Tala asks why the buyers' share differs so much between rice and concert tickets. Which explanation is best?
- Ticket sellers are billed less often than rice sellers, so they bear a smaller share
- Tickets cost more than rice, so the same $1.00 is a smaller share of the ticket price
- The side with fewer alternatives bears more: rice buyers have few substitutes, concert-goers many
- Rice sellers have more market power, so they pass the whole tax on to the buyers of rice
A council member says taxing rice sellers protects shoppers. Zee tests the claim. What is the verdict?
- Not so: shoppers bear the full $1.00, since rice is a necessity that each household must buy
- Not so: shoppers bear about 75 percent, $0.75 of each $1.00, whoever is billed
- Right: sellers pay the tax, so shoppers pay $0.00 more at the register
- Right: with demand elasticity 0.5 shoppers cut back sharply and so pay $0.25 or less