AP Macroeconomics Quiz: Multipliers

What this quiz covers

This quiz focuses on Multipliers, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Macroeconomics.

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. Economy X has a smaller total change in real GDP because more income is saved.
2. Economy X has a larger total change in real GDP because less income leaks to saving each round. (correct answer)
3. Both economies have the same total change in real GDP because $\Delta G$ is the same.
4. Economy Y has a larger total change in real GDP because the MPC is lower.
5. Both economies have zero total change in real GDP because the MPC is less than 1.

Explanation: The multiplier, $1/(1 - MPC)$, amplifies initial spending based on $MPC$ size, with higher $MPC$ meaning fewer saving leakages and larger effects. $MPC$ governs consumption from income, while saving leaks reduce ongoing spending. With $20$ billion spending in both, Economy X's $MPC = 0.9$ yields larger GDP change than Y's $0.6$ due to less leakage per round. Misconceiving equal effects from same initial spending ignores $MPC$'s role in leakage. Identify $MPC$ differences, compute multipliers, and scale initial changes to compare total GDP outcomes.

Question 2

1. Both policies increase real GDP by the same amount.
2. The tax cut increases real GDP more than the spending increase.
3. The spending increase raises real GDP more than the tax cut. (correct answer)
4. The spending increase decreases real GDP while the tax cut increases it.
5. Both policies decrease real GDP by the same amount.

Explanation: Government spending has a larger multiplier effect than tax cuts because spending directly increases GDP while tax cuts only affect GDP through induced consumption. With government spending of $30 billion, the full amount enters the income stream immediately, creating a total GDP change of $30 billion × [1/(1-0.8)] = $30 billion × 5 = $150 billion. With a $30 billion tax cut, only the consumed portion ($30 billion × 0.8 = $24 billion) enters the spending stream initially, creating a total GDP change of $24 billion × 5 = $120 billion. The spending multiplier exceeds the tax multiplier by exactly 1. Students often assume equal-sized fiscal changes have equal effects, missing that tax cuts must first pass through the consumption decision.

Question 3

1. Real GDP increases by $10 billion, and the process ends because firms cannot increase output in the short run.
2. Real GDP increases by $100 billion, and the process ends because saving is a leakage each round. (correct answer)
3. Real GDP increases by $90 billion, and the process ends because the MPC eventually rises to 1.
4. Real GDP increases by $11.1 billion, and the process ends because imports absorb all new spending.
5. Real GDP increases by $10 billion, and the process ends because the multiplier is always equal to 1.

Explanation: The spending multiplier defines the overall GDP boost from new spending, equaling 1/(1 - MPC) when saving is the main leakage, allowing firms to ramp up output in the short run. The MPC propels additional consumption, extending the process, while leakages like saving prevent indefinite continuation by withdrawing funds each round. In this scenario, a $10 billion investment increase with MPC of 0.9 (MPS of 0.1) produces a multiplier of 10, totaling $100 billion in GDP growth, ending due to saving leakages. A misconception is believing the multiplier is always 1, missing how high MPC sustains rounds. The transferable strategy is to identify the MPC to compute the multiplier, then scale the initial change while noting leakages that limit the process.

Question 4

1. Real GDP increases by $40 billion.
2. Real GDP increases by $160 billion. (correct answer)
3. Real GDP increases by $30 billion.
4. Real GDP increases by $120 billion.
5. Real GDP increases by $10 billion.

Explanation: The spending multiplier formula can be expressed as either 1/(1-MPC) or 1/MPS, where MPS is the marginal propensity to save. Since MPC + MPS = 1, when MPS = 0.25, we know MPC = 0.75. The multiplier equals 1/0.25 = 4, meaning each dollar of initial spending ultimately generates $4 of total GDP. With a $40 billion increase in government purchases, the total GDP change is $40 billion × 4 = $160 billion. Students often confuse MPS with the multiplier itself, incorrectly calculating $40 billion × 0.25. Remember: identify whether you're given MPC or MPS, calculate the multiplier as 1/MPS or 1/(1-MPC), then scale the initial change.

Question 5

1. Real GDP increases by $12 billion.
2. Real GDP increases by $20 billion.
3. Real GDP increases by $50 billion. (correct answer)
4. Real GDP increases by $33.3 billion.
5. Real GDP increases by $80 billion.

Explanation: The investment multiplier works identically to the government spending multiplier because both represent direct injections into the spending stream. With MPC = 0.60, the multiplier equals 1/(1-0.60) = 1/0.40 = 2.5. When planned investment rises by $20 billion, this autonomous spending increase circulates through the economy as households spend 60% of each round of new income. The total GDP change equals $20 billion × 2.5 = $50 billion. A common error is thinking investment has a different multiplier than government purchases—it doesn't. The key insight: any autonomous spending component (C, I, G, or NX) uses the same multiplier formula 1/(1-MPC) when it changes independently.

Question 6

1. Real GDP increases by $250 billion.
2. Real GDP increases by $200 billion. (correct answer)
3. Real GDP increases by $50 billion.
4. Real GDP increases by $62.5 billion.
5. Real GDP increases by $40 billion.

Explanation: The tax multiplier differs from the spending multiplier because tax cuts first affect disposable income, and only the consumed portion (MPC × tax cut) enters the spending stream. The tax multiplier equals -MPC/(1-MPC), where the negative sign indicates that tax cuts increase GDP. With MPC = 0.80, the tax multiplier is -0.80/(1-0.80) = -0.80/0.20 = -4. A $50 billion tax cut increases GDP by $50 billion × 4 = $200 billion. Students often mistakenly use the spending multiplier (5) for tax changes, which would incorrectly yield $250 billion. Key strategy: remember that tax changes have a smaller multiplier than spending changes because only MPC × (tax change) is initially spent.

Question 7

1. Real GDP increases by $250 billion. (correct answer)
2. Real GDP increases by $62.5 billion.
3. Real GDP increases by $50 billion.
4. Real GDP increases by $40 billion.
5. Real GDP increases by $200 billion.

Explanation: The spending multiplier measures how much total GDP changes when autonomous spending changes, calculated as $1/(1 - \text{MPC})$ or $1/\text{MPS}$. With MPC = $0.80$, the multiplier equals $1/(1 - 0.80) = 1/0.20 = 5$. When government purchases increase by $50$ billion, this initial injection circulates through the economy as households spend 80% of each round of new income, creating a chain reaction. The total change in GDP equals the initial change times the multiplier: $50$ billion × $5$ = $250$ billion. A common misconception is forgetting to multiply the initial change by the multiplier, which would incorrectly yield only $50$ billion. To solve multiplier problems: first calculate the multiplier using $1/(1 - \text{MPC})$, then multiply by the initial spending change.

Question 8

1. The student treated the initial change as the total change rather than using a multiplier.
2. The student used $1/\text{MPC}$ instead of $1/(1-\text{MPC})$ for the spending multiplier. (correct answer)
3. The student incorrectly assumed imports are a leakage even though only saving matters here.
4. The student should have used the tax multiplier because government purchases are a tax change.
5. The student should have focused on long-run real GDP because multipliers apply only to LRAS.

Explanation: The student's error reveals a common misunderstanding of the multiplier formula. They used 1/MPC instead of the correct formula 1/(1-MPC) for the spending multiplier. With MPC = 0.60, the correct multiplier is 1/(1-0.60) = 1/0.40 = 2.5, not 1/0.60 = 1.67. The total GDP change should be $15 billion × 2.5 = $37.5 billion, not $25 billion. This mistake often occurs because students confuse the fraction saved (1-MPC) with the fraction consumed (MPC). The denominator must be the fraction that leaks out (saving), not the fraction that continues circulating. Remember: the multiplier formula uses 1 minus MPC because we need to account for what doesn't get respent in each round.

Question 9

1. $80 billion
2. $100 billion
3. $180 billion
4. $400 billion
5. $500 billion (correct answer)

Explanation: The spending multiplier shows how an initial change in spending creates a larger total change in GDP through successive rounds of spending. With an MPC of 0.80, when households receive new income, they spend 80% and save 20%, creating a chain reaction. The multiplier formula is 1/(1-MPC) = 1/(1-0.80) = 1/0.20 = 5. When government increases purchases by $100 billion, this initial injection gets multiplied: $100 billion × 5 = $500 billion total change in GDP. A common mistake is forgetting that the initial spending itself counts as part of the total change. To solve multiplier problems: first calculate the multiplier using 1/(1-MPC), then multiply by the initial change to find the total effect.

Question 10

1. An increase of $40 billion
2. An increase of $120 billion (correct answer)
3. An increase of $160 billion
4. An increase of $90 billion
5. An increase of $53 billion

Explanation: Tax cuts affect GDP through the consumption they generate, not the full amount of the cut. With an MPC of 0.75, households consume 75% of the $40 billion tax cut ($30 billion) and save 25% ($10 billion). Only the consumed portion enters the spending stream and gets multiplied by the spending multiplier of 1/(1-0.75) = 4. The total GDP increase equals $30 billion × 4 = $120 billion, or equivalently, $40 billion × 0.75 × 4 = $120 billion. A common error is multiplying the entire tax cut by the spending multiplier, yielding $160 billion, without recognizing that part of the tax cut is immediately saved. The tax multiplier equals MPC × spending multiplier = 0.75 × 4 = 3, so $40 billion × 3 = $120 billion. The strategy for tax changes is to either apply the tax multiplier directly or calculate the initial consumption from the tax cut, then apply the spending multiplier.

Question 11

1. $40\text{ billion}$
2. $50\text{ billion}$
3. $100\text{ billion}$
4. $250\text{ billion}$ (correct answer)
5. $400\text{ billion}$

Explanation: The spending multiplier shows how an initial change in spending creates a larger total change in GDP through successive rounds of spending. With an MPC of 0.8, households spend 80% of each new dollar of income they receive. The multiplier formula is 1/(1-MPC) = 1/(1-0.8) = 1/0.2 = 5. When the government increases purchases by $50 billion, this creates $50 billion in new income, of which $40 billion is spent (creating more income), then $32 billion, and so on. The total change in GDP equals the initial spending times the multiplier: $50 billion × 5 = $250 billion. A common mistake is forgetting that the initial spending itself counts as part of the total GDP change.

Question 12

1. Because each round of spending creates new income that is partly spent again. (correct answer)
2. Because government spending permanently raises long-run economic growth.
3. Because the initial $20\text{ billion}$ increase is counted multiple times in GDP.
4. Because saving rises by more than income rises in each successive round.
5. Because the price level must fall when aggregate demand increases.

Explanation: The spending multiplier exceeds 1 because initial spending creates income that gets partially re-spent in successive rounds, creating a chain reaction. With an MPC of 0.75, when the government spends $20 billion, recipients spend $15 billion of this new income, which becomes income for others who spend $11.25 billion, and so on. Each round adds to total GDP, making the final impact larger than the initial spending. The multiplier equals 1/(1-0.75) = 4, so total GDP rises by $80 billion. Option A correctly identifies this circular flow mechanism. Common misconceptions include thinking the initial amount gets counted multiple times (it doesn't—each round represents new transactions) or that saving increases faster than income (saving is a constant fraction of income).

Question 13

1. The multiplier becomes larger because higher saving increases funds available for consumption.
2. The multiplier becomes smaller because higher saving reduces spending in later rounds. (correct answer)
3. The multiplier becomes infinite because saving delays spending to future periods.
4. The multiplier is unchanged because only the initial $40 billion affects real GDP.
5. The multiplier becomes larger because the tax multiplier is negative when saving rises.

Explanation: The spending multiplier quantifies the total output change from new expenditures, defined as 1/(1 - MPC) and influenced by leakages that alter its size. The MPC supports expansion through respending, but increased leakages like higher saving (larger MPS) reduce the multiplier by curtailing later rounds. In this scenario, raising saving from an MPC of 0.8 decreases the multiplier below 5 for a $40 billion spending change, as more income leaks out, leading to smaller total GDP growth. A misconception is thinking higher saving enlarges the multiplier via more investment funds, but it actually diminishes immediate spending effects. The transferable strategy is to identify the MPC (adjusting for leakage changes), compute the updated multiplier, and scale the initial change to evaluate impacts.

Question 14

1. The tax cut, because the tax multiplier equals $1/\text{MPC}$ in the short run.
2. The spending increase, because the spending multiplier exceeds the tax multiplier for the same dollar change. (correct answer)
3. The tax cut, because the spending multiplier equals MPC and is less than 1.
4. The spending increase, because the multiplier effect occurs only for government spending, not taxes.
5. Both policies, because any fiscal policy change has a multiplier of 1 in the short run.

Explanation: The spending multiplier and tax multiplier differ because government purchases directly inject the full amount into the spending stream, while tax cuts only inject MPC times the tax cut. With MPC = 0.75, the spending multiplier is 1/(1-0.75) = 4, while the tax multiplier is -0.75/(1-0.75) = -3. For a $40 billion change, government spending increases GDP by $40 billion × 4 = $160 billion, while tax cuts increase GDP by $40 billion × 3 = $120 billion. The spending increase has a larger effect because the entire $40 billion enters the circular flow immediately, whereas with tax cuts, only $30 billion (0.75 × $40 billion) is initially spent. Misconception alert: the multiplier effect applies to both policies, not just government spending. Strategy: compare multipliers before calculating total effects.

Question 15

1. Multiplier $=1.5$ and real GDP increases by $67.5 billion.
2. Multiplier $=2.5$ and real GDP increases by $112.5 billion. (correct answer)
3. Multiplier $=0.60$ and real GDP increases by $27 billion.
4. Multiplier $=1.0$ and real GDP increases by $45 billion.
5. Multiplier $=3.0$ and real GDP increases by $135 billion.

Explanation: The government spending multiplier formula is $1/(1-\text{MPC})$, which represents how much total GDP changes per dollar of government purchases. With $\text{MPC} = 0.60$, the multiplier equals $1/(1-0.60) = 1/0.40 = 2.5$. This means each dollar of government spending ultimately increases GDP by $2.50 through the circular flow of income and consumption. For a $45 billion increase in government purchases, the total GDP change equals $45 billion × 2.5 = $112.5 billion. Students sometimes confuse the multiplier with MPC itself (0.60) or calculate 1/MPC instead of 1/(1-MPC). Remember the strategy: the multiplier is always greater than 1 when MPC > 0, and equals 1/(1-MPC) for any autonomous spending change.

Question 16

1. Because each round of spending creates additional income that leads to further consumption spending. (correct answer)
2. Because the increase in government purchases permanently raises long-run economic growth.
3. Because the multiplier equals 1 whenever $MPC$ is less than 1.
4. Because saving is zero in the circular flow when $MPC$ equals 0.80.
5. Because imports and taxes are assumed to increase the size of the multiplier.

Explanation: The multiplier effect occurs because each dollar of spending becomes income for someone else, who then spends a fraction ($MPC$) of it, creating more income in a continuing cycle. With $MPC$ = 0.80, the initial $30 billion government purchase leads to $24 billion of induced consumption (0.80 × $30 billion), then $19.2 billion (0.80 × $24$ billion), and so on. This geometric series sums to $30 billion × [1/(1-0.80)] = $30 billion × 5 = $150 billion total. The key insight is that spending creates income, which creates more spending—a circular flow that amplifies the initial injection. Common misconceptions include thinking the multiplier equals $MPC$ or that saving prevents any multiplier effect. Strategy: visualize the spending rounds as a shrinking series that sums to initial change times 1/(1-$MPC$).

Question 17

1. $50 billion
2. $100 billion
3. $200 billion
4. $250 billion (correct answer)
5. $40 billion

Explanation: The spending multiplier measures how much total GDP changes from an initial change in spending, calculated as $1/(1 - MPC)$, where MPC is the marginal propensity to consume. The MPC represents the portion of additional income spent on consumption, while leakages like saving reduce the multiplier effect by removing money from the spending cycle. In this scenario, with $MPC = 0.8$ and an initial government spending increase of $50 billion, the multiplier is $5$, leading to a total GDP increase of $250 billion as rounds of spending amplify the initial injection. A common misconception is thinking the total change equals only the initial spending, ignoring induced consumption from subsequent income gains. To apply this transferably, first identify the MPC to compute the multiplier, then scale the initial spending change by that multiplier to find the total GDP shift.

Question 18

1. $45 billion
2. $60 billion
3. $80 billion
4. $180 billion
5. $240 billion (correct answer)

Explanation: The multiplier effect occurs because each dollar of new spending becomes income for someone else, who then spends part of it, creating more income in a continuing cycle. With MPC = 0.75, households spend 75% of additional income and save 25%, which is the only leakage here. The spending multiplier equals 1/(1-MPC) = 1/(1-0.75) = 1/0.25 = 4. When firms increase investment by $60 billion, this initial injection multiplies through the economy: $60 billion × 4 = $240 billion total change in GDP. Students often confuse the initial change with the total change—remember the initial spending gets magnified. The strategy is always: identify MPC, calculate multiplier as 1/(1-MPC), then scale the initial change.

Question 19

1. The initial $20$ billion is counted repeatedly in GDP each round of spending.
2. Higher investment automatically raises long-run potential output by the same amount.
3. Each round of new income induces additional consumption spending until leakages reduce the process. (correct answer)
4. The multiplier is always infinite when the MPC is less than 1.
5. The tax credit increases government purchases, which has no leakage from saving.

Explanation: The multiplier effect occurs when an initial spending change leads to further rounds of income and consumption, with the size determined by $1/(1 - \text{MPC})$. The $\text{MPC}$ dictates how much of new income is respent, while leakages such as saving diminish each round's impact. Here, the $20$ billion investment increase, with $\text{MPC} = 0.75$, generates additional consumption in each cycle until saving leakages halt the process, making total GDP change exceed $20$ billion. One misconception is believing the multiplier is infinite if $\text{MPC}$ < 1, but it converges due to leakages. For any similar problem, spot the $\text{MPC}$ to derive the multiplier, then multiply it by the initial change to estimate total output effects.

Question 20

1. 0.20
2. 0.80
3. 1.25
4. 4
5. 5 (correct answer)

Explanation: The spending multiplier formula is 1/(1-MPC), where MPC is the marginal propensity to consume. This formula captures how initial spending circulates through the economy in diminishing rounds. With MPC = 0.80, households spend 80% of additional income and save 20%. The multiplier equals 1/(1-0.80) = 1/0.20 = 5. This means each dollar of initial spending ultimately creates five dollars of total GDP change. A common error is using MPC directly as the multiplier or calculating 1/MPC instead of 1/(1-MPC). Remember the intuition: the multiplier must be greater than 1 because the initial spending itself counts, plus all the subsequent rounds of respending.