AP Microeconomics Quiz: Market Disequilibrium And Changes In Equilibrium

What this quiz covers

This quiz focuses on Market Disequilibrium And Changes In Equilibrium, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Microeconomics.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. Both the equilibrium price and quantity of jelly will increase. (correct answer)
2. Both the equilibrium price and quantity of jelly will decrease.
3. The equilibrium price of jelly will increase, and the quantity will decrease.
4. The equilibrium price of jelly will decrease, and the quantity will increase.

Explanation: Cheaper peanuts will increase the supply of peanut butter, lowering its price. Since peanut butter and jelly are complements, a lower price for peanut butter will increase the demand for jelly. An increase in demand for jelly will lead to a higher equilibrium price and a higher equilibrium quantity of jelly.

Question 2

1. The equilibrium price will increase, and the equilibrium quantity will decrease. (correct answer)
2. The equilibrium price will decrease, and the equilibrium quantity will decrease.
3. The equilibrium price will be indeterminate, and the equilibrium quantity will decrease.
4. The equilibrium price will increase, and the equilibrium quantity will be indeterminate.

Explanation: A decrease in demand pushes price and quantity down. A decrease in supply pushes price up and quantity down. Both shifts cause quantity to decrease, so the equilibrium quantity will definitely decrease. Since the decrease in supply (which pushes price up) is larger than the decrease in demand (which pushes price down), the net effect is an increase in the equilibrium price.

Question 3

1. An increase in price and a decrease in quantity. (correct answer)
2. A decrease in price and an increase in quantity.
3. An increase in price and an increase in quantity.
4. A decrease in price and a decrease in quantity.

Explanation: The destruction of the cocoa crop, a key input for chocolate, will decrease the supply of chocolate bars (shift the supply curve to the left). A decrease in supply results in a higher equilibrium price and a lower equilibrium quantity.

Question 4

1. The equilibrium price will increase, but the equilibrium quantity will remain the same. (correct answer)
2. Both the equilibrium price and the equilibrium quantity will increase significantly.
3. The equilibrium price will remain the same, but the quantity will increase.
4. A shortage will be created, but the price will not change due to the fixed supply.

Explanation: Perfectly inelastic supply means the quantity supplied is fixed and does not change regardless of price (a vertical supply curve). Increased public desire means an increase in demand (a rightward shift of the demand curve). This will cause the equilibrium price to rise, but the equilibrium quantity cannot change because it is fixed.

Question 5

1. Equilibrium price rises and equilibrium quantity rises (correct answer)
2. Equilibrium price falls and equilibrium quantity rises
3. Equilibrium price rises and equilibrium quantity falls
4. Equilibrium price falls and equilibrium quantity falls
5. Equilibrium price and quantity do not change because this is a movement along $D_1$

Explanation: This question tests the skill of analyzing changes in equilibrium. Market equilibrium occurs when quantity demanded (QD) equals quantity supplied (QS) at the equilibrium price; a shortage exists when QD > QS at a given price, while a surplus exists when QS > QD. On the graph, the shift from D1 to D2 moves the intersection with the supply curve from E1 to E2, showing a higher price and quantity. From the graph, E2 is at a higher price and quantity than E1, justifying choice A that equilibrium price rises and quantity rises. A common misconception is thinking this is a movement along D1, but it's a shift in demand increasing both price and quantity. A transferable strategy is to always compare QD and QS at the same price; shifts change equilibrium, not movements along. Shortages push prices up, surpluses down, guiding adjustments to new equilibria.

Question 6

1. Shortage of $4$ units
2. Surplus of $4$ units (correct answer)
3. Shortage of $2$ units
4. Surplus of $2$ units
5. No shortage or surplus; the market is in equilibrium at $P_1$

Explanation: This question tests the skill of identifying market disequilibrium. Market equilibrium occurs when quantity demanded (QD) equals quantity supplied (QS) at the equilibrium price; a shortage exists when QD > QS at a given price, while a surplus exists when QS > QD. On the graph, at the price of P1=7, QD is read from the price line to the demand curve, and QS to the supply curve. From the graph, at P1=7, QS exceeds QD by 4 units, creating a surplus of 4 units, justifying choice B as correct. A common misconception is confusing the adjustment direction, thinking surplus raises price, but it actually pushes price down. A transferable strategy is to always compare QD and QS at the same price; surpluses push prices down toward equilibrium. Shifts in curves change the equilibrium, unlike movements along caused by price changes.

Question 7

1. Equilibrium price will increase, and equilibrium quantity will increase. (correct answer)
2. Equilibrium price will decrease, and equilibrium quantity will increase.
3. Equilibrium price will increase, and equilibrium quantity will decrease.
4. Equilibrium price will decrease, and equilibrium quantity will decrease.

Explanation: An increase in consumer incomes will cause the demand for a normal good, like smartphones, to increase (shift to the right). This shift leads to a higher equilibrium price and a higher equilibrium quantity.

Question 8

1. Surplus of $6$ units
2. Shortage of $6$ units (correct answer)
3. Surplus of $3$ units
4. Shortage of $3$ units
5. No shortage or surplus; the market is in equilibrium at $P_1$

Explanation: This question tests the skill of identifying market disequilibrium. Market equilibrium occurs when quantity demanded (QD) equals quantity supplied (QS) at the equilibrium price; a shortage exists when QD > QS at a given price, while a surplus exists when QS > QD. On the graph, at the price of P1=3, QD is found by reading from the price line to the demand curve, and QS to the supply curve. From the graph, at P1=3, QD exceeds QS by 6 units, creating a shortage of 6 units, justifying choice B as correct. A common misconception is reversing shortage and surplus, but when price is below equilibrium, buyers demand more than supplied, causing shortage. A transferable strategy is to always compare QD and QS at the same price; shortages push prices up toward equilibrium. Shifts in curves change the equilibrium, unlike movements along due to price changes.

Question 9

1. Shortage of $6$ units
2. Surplus of $6$ units (correct answer)
3. Shortage of $3$ units
4. Surplus of $3$ units
5. No shortage or surplus; the market is in equilibrium at $P_f$

Explanation: This question tests the skill of identifying market disequilibrium. Market equilibrium occurs when quantity demanded (QD) equals quantity supplied (QS) at the equilibrium price; a shortage exists when QD > QS at a given price, while a surplus exists when QS > QD. On the graph, at the price floor of Pf=9, QD is determined by the price line intersecting the demand curve, and QS the supply curve. From the graph, at Pf=9, QS exceeds QD by 6 units, creating a surplus of 6 units, justifying choice B as correct. A common misconception is thinking a high price floor causes shortage, but it actually leads to surplus as supply outpaces demand. A transferable strategy is to always compare QD and QS at the same price; surpluses push prices down toward equilibrium. Shifts in demand or supply change the equilibrium point, not movements along the curves.

Question 10

1. $P^* = 6$ and $Q^* = 8$
2. $P^* = 5$ and $Q^* = 8$
3. $P^* = 5$ and $Q^* = 6$ (correct answer)
4. $P^* = 6$ and $Q^* = 6$
5. $P^* = 7$ and $Q^* = 10$

Explanation: This question tests the skill of analyzing changes in equilibrium. Market equilibrium occurs when quantity demanded (QD) equals quantity supplied (QS) at the equilibrium price; a shortage exists when QD > QS at a given price, while a surplus exists when QS > QD. On the graph, the shift from D1 to D2 moves the intersection with the supply curve from E1 to a new E2. From the graph, the new equilibrium E2 is at P*=5 and Q*=6, justifying choice C as the correct answer. A common misconception is thinking price falls but quantity rises with demand decrease, but both fall due to the leftward shift. A transferable strategy is to always compare QD and QS at the same price; shifts change equilibrium, not movements along. Surpluses push prices down, shortages up, adjusting to the new equilibrium.

Question 11

1. A shortage will be created, which will exert upward pressure on the price. (correct answer)
2. A surplus will be created, which will exert downward pressure on the price.
3. The supply curve for coffee will shift to the right to meet the higher demand.
4. The demand curve for coffee will shift to the left to restore the market to equilibrium.

Explanation: When the price is below equilibrium, the quantity demanded exceeds the quantity supplied, creating a shortage (or excess demand). Buyers will compete for the limited goods, bidding the price up toward the equilibrium level.

Question 12

1. Equilibrium quantity will increase; the effect on equilibrium price is indeterminate. (correct answer)
2. Equilibrium price will increase; the effect on equilibrium quantity is indeterminate.
3. Equilibrium quantity will decrease; the effect on equilibrium price is indeterminate.
4. Equilibrium price will decrease, and equilibrium quantity will increase.

Explanation: Increased consumer preference shifts demand to the right, which increases both price and quantity. Lower production costs shift supply to the right, which decreases price and increases quantity. Since both effects increase quantity, the equilibrium quantity will definitely increase. However, the price effect is indeterminate because the demand shift pushes the price up while the supply shift pushes it down.

Question 13

1. The equilibrium price will increase; the effect on equilibrium quantity is indeterminate. (correct answer)
2. The equilibrium quantity will decrease; the effect on equilibrium price is indeterminate.
3. Both the equilibrium price and quantity will increase, but the price increase will be larger.
4. The equilibrium price will decrease, and the equilibrium quantity will be indeterminate.

Explanation: The influx of new residents increases the demand for apartments (demand shifts right), which pushes price and quantity up. The demolition of buildings decreases the supply of apartments (supply shifts left), which pushes price up and quantity down. Since both shifts cause the price to rise, the equilibrium price will definitely increase. The effect on quantity is indeterminate because the demand shift increases it while the supply shift decreases it.

Question 14

1. The equilibrium price will decrease; the effect on equilibrium quantity is indeterminate. (correct answer)
2. The equilibrium quantity will increase; the effect on equilibrium price is indeterminate.
3. Both the equilibrium price and quantity will decrease, but the effect on quantity is larger.
4. The equilibrium price will increase; the effect on equilibrium quantity is indeterminate.

Explanation: Increased health concerns will decrease the demand for sugary sodas (demand shifts left), causing price and quantity to fall. A fall in the price of corn syrup will increase the supply (supply shifts right), causing price to fall and quantity to rise. Because both events cause the price to fall, the equilibrium price will definitely decrease. The equilibrium quantity is indeterminate because the demand shift decreases it while the supply shift increases it.

Question 15

1. Price will increase, and quantity will increase. (correct answer)
2. Price will decrease, and quantity will increase.
3. Price will be indeterminate, and quantity will increase.
4. Price will increase, and quantity will be indeterminate.

Explanation: Both an increase in demand and an increase in supply will cause the equilibrium quantity to increase. The increase in demand puts upward pressure on price, while the increase in supply puts downward pressure on price. Since the increase in demand is large and the increase in supply is small, the upward pressure on price will outweigh the downward pressure, causing the equilibrium price to increase.

Question 16

1. The price will increase more in Market B than in Market A. (correct answer)
2. The price will increase more in Market A than in Market B.
3. The quantity will increase more in Market B than in Market A.
4. The price increase will be identical in both markets.

Explanation: When supply is highly inelastic, producers cannot easily increase the quantity supplied in response to a price change. Therefore, an increase in demand will lead to a large increase in price but only a small increase in quantity. When supply is highly elastic, producers can easily increase quantity, so the same demand shift results in a smaller price increase and a larger quantity increase. Thus, price increases more in Market B.

Question 17

1. Equilibrium quantity will decrease; the effect on equilibrium price is indeterminate. (correct answer)
2. Equilibrium price will increase; the effect on equilibrium quantity is indeterminate.
3. Equilibrium quantity will increase; the effect on equilibrium price is indeterminate.
4. Both equilibrium price and quantity will decrease, and the effects will be equal.

Explanation: The shift in preferences to online news decreases the demand for print newspapers (demand shifts left), which lowers both price and quantity. The rising cost of paper, an input, decreases the supply (supply shifts left), which raises the price and lowers the quantity. Since both effects cause quantity to fall, the equilibrium quantity will definitely decrease. The effect on price is indeterminate because the demand shift pushes it down while the supply shift pushes it up.

Question 18

1. $P^* = 5$ and $Q^* = 10$
2. $P^* = 7$ and $Q^* = 6$ (correct answer)
3. $P^* = 6$ and $Q^* = 8$
4. $P^* = 7$ and $Q^* = 8$
5. $P^* = 6$ and $Q^* = 10$

Explanation: This question tests the skill of analyzing changes in equilibrium. Market equilibrium occurs when quantity demanded (QD) equals quantity supplied (QS) at the equilibrium price; a shortage exists when QD > QS at a given price, while a surplus exists when QS > QD. On the graph, the shift from S1 to S2 moves the intersection with the demand curve from E1 to a new E2. From the graph, the new equilibrium E2 is at P*=7 and Q*=6, justifying choice B as the correct answer. A common misconception is expecting quantity to rise with a supply decrease, but a leftward shift reduces quantity and raises price. A transferable strategy is to always compare QD and QS at the same price; shifts change equilibrium, not movements along. Shortages push prices up, surpluses down, leading to the new equilibrium point.

Question 19

1. Equilibrium price rises and equilibrium quantity rises
2. Equilibrium price rises and equilibrium quantity falls
3. Equilibrium price falls and equilibrium quantity rises (correct answer)
4. Equilibrium price falls and equilibrium quantity falls
5. Equilibrium price and quantity do not change because this is a movement along $S_1$

Explanation: This question tests the skill of analyzing changes in equilibrium. Market equilibrium occurs when quantity demanded ($QD$) equals quantity supplied ($QS$) at the equilibrium price; a shortage exists when $QD$ > $QS$ at a given price, while a surplus exists when $QS$ > $QD$. On the graph, the shift from $S_1$ to $S_2$ moves the intersection with the demand curve from $E_1$ to $E_2$, showing a lower price and higher quantity. From the graph, $E_2$ reflects a fall in price and rise in quantity, justifying choice C as correct. A common misconception is believing supply increase raises price, but it actually lowers price and increases quantity. A transferable strategy is to always compare $QD$ and $QS$ at the same price; shifts change equilibrium, not movements along. Surpluses from shifts push prices down, shortages up, reaching new equilibrium.

Question 20

1. $P^* = 6$ and $Q^* = 8$
2. $P^* = 8$ and $Q^* = 8$
3. $P^* = 7$ and $Q^* = 10$ (correct answer)
4. $P^* = 7$ and $Q^* = 8$
5. $P^* = 6$ and $Q^* = 10$

Explanation: This question tests the skill of analyzing changes in equilibrium. Market equilibrium occurs when quantity demanded (QD) equals quantity supplied (QS) at the equilibrium price; a shortage exists when QD > QS at a given price, while a surplus exists when QS > QD. On the graph, the shift from D1 to D2 moves the intersection with the supply curve from E1 to a new E2. From the graph, the new equilibrium E2 is at P*=7 and Q*=10, justifying choice C as the correct answer. A common misconception is thinking demand increase lowers price, but it raises both price and quantity. A transferable strategy is to always compare QD and QS at the same price; shifts change equilibrium, not movements along. Shortages push prices up, surpluses down, leading to the new equilibrium point.