The Aggregate Demand-Aggregate Supply Model - AP Macroeconomics

1. Based on the AD–AS model shown, the economy moves from $E_1$ to $E_2$ as aggregate demand shifts left from $AD_1$ to $AD_2$ in the short run. Which of the following is the most plausible cause of the shift shown?
   Answer: A decrease in the money supply that raises interest rates. The graph shows aggregate demand shifting left from AD₁ to AD₂, moving the economy down along SRAS to E₂ with both a lower price level and lower real GDP. Among the options, only a decrease in money supply that raises interest rates would shift AD leftward—higher interest rates discourage borrowing and spending by both consumers and businesses, reducing aggregate demand. More infrastructure spending would shift AD right, while lower oil prices, higher productivity, and lower nominal wages all cut firms' costs and shift SRAS right rather than AD. A common error is confusing which policies affect which curves; monetary and fiscal policies primarily shift AD, while cost and productivity changes shift SRAS. The strategy is to match the direction and curve of the shift shown (leftward AD) with policies that reduce spending.
2. Based on the AD–AS model shown, suppose a fall in nominal wages reduces firms' per-unit costs, shifting short-run aggregate supply. In the short run, which of the following best describes the change from $E_1$ to the new short-run equilibrium?
   Answer: The price level decreases and real GDP increases in the short run. When nominal wages fall, firms' per-unit production costs decrease, making production more profitable at any given price level—this shifts the SRAS curve rightward from SRAS1. The new SRAS crosses the unchanged AD curve down and to the right of E1, so the move to the new short-run equilibrium brings a lower price level but higher real GDP in the short run. A common misconception is thinking wage changes affect demand rather than supply, but wages are an input cost affecting the supply side. The analytical strategy is recognizing that rightward SRAS shifts (from lower costs) always create this beneficial combination: lower prices with higher output, moving down along the AD curve.
3. Based on the AD–AS model shown, suppose a rapid increase in nominal wages raises firms' per-unit costs, shifting short-run aggregate supply in the short run. Which description correctly compares the initial equilibrium $E_1$ with the new short-run equilibrium?
   Answer: The price level rises and real GDP falls. Labor is the largest cost for most firms, so a rapid rise in nominal wages pushes up per-unit production costs and shifts the SRAS curve leftward from SRAS₁. The new SRAS crosses the unchanged AD curve up and to the left of E₁, so the new short-run equilibrium has a higher price level but lower real GDP. This illustrates wage-push inflation, a type of cost-push inflation where higher labor costs reduce supply while raising prices. A key misconception is thinking wage increases always benefit the economy—in the short run, they can cause stagflation. The diagnostic strategy is recognizing that leftward SRAS shifts (from any cost increase) force the economy up along the AD curve, raising prices while reducing output.
4. Based on the AD–AS model shown, the economy is initially at equilibrium $E_1$. A central bank conducts contractionary monetary policy that reduces aggregate demand, shifting it from $AD_1$. Which of the following best describes the short-run outcome?
   Answer: The price level falls and real GDP falls in the short run. Contractionary monetary policy raises interest rates (or slows money growth), which discourages investment and interest-sensitive consumption, so aggregate demand shifts leftward from AD1. A leftward shift of AD crosses the unchanged SRAS curve down and to the left of E1, so the new short-run equilibrium has both a lower price level and lower real GDP. Students sometimes expect only prices to fall with tight money, but the short-run trade-off means output falls too. The key strategy for monetary policy analysis is remembering that contractionary policy shifts AD left (reducing spending), while expansionary policy shifts AD right, with corresponding effects on both prices and output.
5. Based on the AD–AS model shown, an inflationary shock occurs and the economy moves from E1 to E2 as short-run aggregate supply shifts from SRAS1 to SRAS2. Which of the following best describes whether the shock is demand-pull or cost-push, and the direction of change in the price level and real GDP in the short run?
   Answer: Cost-push; the price level rises and real GDP falls in the short run. The AD-AS model equilibrium, where aggregate demand meets short-run aggregate supply, determines the economy's price level and real GDP. The graph shows SRAS shifting leftward from SRAS1 to SRAS2, moving from E1 to E2 with higher prices but lower output—this is cost-push inflation. Cost-push inflation occurs when rising production costs (like oil prices or wages) shift SRAS left, while demand-pull inflation involves AD shifting right. The key distinction is that cost-push creates stagflation (higher prices with lower output), while demand-pull raises both. Students often mislabel all inflation as demand-pull, but the strategy is examining which curve shifts and the resulting price-output combination: leftward SRAS shifts always indicate cost-push inflation.
6. Based on the AD–AS model shown, a natural disaster disrupts supply chains, shifting short-run aggregate supply leftward from $SRAS_1$ in the short run. Which statement correctly identifies the type of change and its effects?
   Answer: Cost-push; the price level rises and real GDP falls. A natural disaster that breaks supply chains makes inputs scarce and costly and reduces firms' ability to produce, shifting SRAS leftward from SRAS₁. The unchanged AD curve now meets the new SRAS up and to the left of E₁, so the new short-run equilibrium has a higher price level but lower real GDP—this is cost-push inflation because rising costs push prices up while reducing output. This represents a negative supply shock causing stagflation (stagnant growth with inflation). Students often confuse supply disruptions with demand changes, but supply problems shift SRAS, not AD. The key insight is that leftward SRAS shifts force the economy up along the AD curve, creating the problematic combination of higher prices with lower output.
7. Based on the AD–AS model shown, suppose consumer confidence rises and households increase spending, which shifts aggregate demand in the short run. Which of the following correctly describes the change from $E_1$ to the new short-run equilibrium?
   Answer: The price level rises and real GDP rises. A rise in consumer confidence lifts consumption, the largest component of aggregate demand, so households buy more output at every price level and the AD curve shifts rightward from AD₁. Because SRAS slopes upward, a rightward shift of AD crosses it up and to the right of E₁, so the new short-run equilibrium has both a higher price level and higher real GDP. This illustrates demand-pull effects where increased spending pulls prices up while expanding output. A common misconception is confusing short-run effects (movement along SRAS) with long-run adjustments (shifts in SRAS). The key strategy is to identify which curve shifts first—here it's AD shifting right—then trace the new intersection point to determine changes in both price level and output.
8. Based on the AD–AS model shown, assume the economy is initially at equilibrium $E_1$. A reduction in business taxes increases planned investment, shifting aggregate demand. Which statement correctly identifies the short-run effects on real GDP and the price level?
   Answer: Real GDP increases and the price level increases in the short run. Cutting business taxes raises the after-tax return on new plants and equipment, so firms increase investment spending and the AD curve shifts rightward from AD1. A rightward shift of AD meets the unchanged SRAS curve up and to the right of E1, so the new short-run equilibrium has both a higher price level and higher real GDP. The strategy is to identify which spending component changes (investment increases), determine the curve affected (AD shifts right), and trace the new equilibrium along the upward-sloping SRAS.
9. Based on the AD–AS model shown, the economy moves from $E_1$ to $E_2$ as short-run aggregate supply shifts right from $SRAS_1$ to $SRAS_2$ in the short run. Which of the following is the most plausible cause of the shift shown?
   Answer: A decrease in input prices that lowers firms' per-unit costs. In the graph, SRAS₁ shifts right to SRAS₂ while AD stays put, so the economy slides down along AD from E₁ to E₂, reaching a lower price level and higher real GDP. Only a decrease in input prices would shift SRAS rightward—lower input costs reduce firms' per-unit production costs, enabling them to supply more at any price level. Higher consumer wealth, lower business taxes that spur investment, more government purchases, and lower interest rates all affect aggregate demand rather than short-run aggregate supply. Students often confuse demand-side and supply-side factors; remember that SRAS shifts result from changes in production costs or productivity, not spending changes. The diagnostic approach is recognizing that rightward SRAS shifts must stem from factors that reduce costs or increase productivity, making production more profitable.
10. Based on the AD–AS model shown, suppose a decrease in consumer confidence causes aggregate demand to shift. In the short run, which of the following correctly describes the change in the price level and real GDP from the initial equilibrium ($E_1$) to the new short-run equilibrium?
    Answer: The price level decreases and real GDP decreases in the short run. When households grow less confident about their jobs and incomes, they cut consumption, and that lower spending shifts the AD curve leftward from AD1. With SRAS unchanged, a leftward shift of AD crosses SRAS down and to the left of E1, so the new short-run equilibrium has both a lower price level and lower real GDP. A common misconception is confusing movements along a curve with shifts of the curve—here, the entire AD curve shifts left, not just a movement along it. The key strategy is to identify which curve shifts first (AD shifts left due to decreased confidence), then trace the new intersection point to see how both price level and output change.
11. Based on the AD–AS model shown, suppose a sharp increase in oil prices raises firms' production costs, shifting short-run aggregate supply from SRAS1. In the short run, what happens to the price level and real GDP from the initial equilibrium (E1) to the new short-run equilibrium?
    Answer: The price level increases and real GDP decreases in the short run. An oil-price shock is a supply-side event: it raises production costs for firms across the economy, so SRAS shifts leftward (upward) from SRAS1 while AD stays put. A leftward SRAS shift crosses the unchanged AD curve up and to the left of E1, so the new short-run equilibrium has a higher price level but lower real GDP—this combination is called stagflation. Students often mistakenly think supply shocks affect only prices or only output, but they impact both simultaneously in opposite directions. The strategy for analyzing supply shocks is to remember that leftward SRAS shifts always create this inverse relationship: prices rise while output falls in the short run.
12. Based on the AD–AS model shown, the economy moves from equilibrium E1 to equilibrium E2 after aggregate demand shifts from AD1 to AD2. Which of the following is the most likely cause of the shift shown?
    Answer: An increase in government purchases that raises aggregate demand. The AD-AS equilibrium represents where aggregate demand intersects short-run aggregate supply, determining both price level and real GDP for the economy. The graph shows AD shifting rightward from AD1 to AD2, moving equilibrium from E1 to E2 with both higher prices and higher output. Among the options, only an increase in government purchases directly shifts AD rightward—government spending is a component of aggregate demand (C + I + G + NX). Students often confuse single-product price changes with aggregate price level changes, but individual product prices don't shift AD curves. The key strategy is distinguishing between factors that shift AD (spending components), SRAS (production costs), and LRAS (potential output), then matching the observed shift pattern.
13. Based on the AD–AS model shown, the economy moves from equilibrium E1 to equilibrium E2 after short-run aggregate supply shifts from SRAS1 to SRAS2. Which of the following events is most consistent with the shift shown?
    Answer: A decrease in expected inflation that increases short-run aggregate supply. In the AD-AS framework, equilibrium is determined by the intersection of aggregate demand and short-run aggregate supply curves, establishing price level and real GDP. The graph shows SRAS shifting rightward from SRAS1 to SRAS2, moving equilibrium from E1 to E2. A decrease in expected inflation reduces workers' wage demands and firms' pricing expectations, lowering production costs and shifting SRAS rightward. This results in lower prices and higher output at E2. Students often confuse expected inflation with actual price level changes—expected inflation affects supply decisions before actual prices adjust. The strategy for identifying SRAS shifts is to look for factors affecting production costs or expectations, not spending patterns which would shift AD instead.
14. Based on the AD–AS model shown, assume a temporary increase in payroll taxes reduces households' disposable income, shifting aggregate demand leftward from $AD_1$ in the short run. Starting from $E_1$, which change occurs at the new short-run equilibrium?
    Answer: The price level falls and real GDP falls. A payroll tax increase takes money out of every paycheck, so households cut consumption and aggregate demand shifts leftward from AD₁. A leftward shift of AD crosses the unchanged SRAS curve down and to the left of E₁, so the new short-run equilibrium sits lower on SRAS, with both a lower price level and lower real GDP. This represents contractionary fiscal policy's effects—reduced spending leads to lower output and some deflation. Students often confuse the direction of shifts; remember that policies reducing spending shift AD left, not right. The strategy is to identify that decreased disposable income shifts AD left, then trace the new intersection down along SRAS to find lower prices and output.
15. Based on the AD–AS model shown, the economy starts at $E_1$ when the central bank purchases government securities, increasing the money supply and shifting aggregate demand in the short run. Which statement correctly compares the new short-run equilibrium with $E_1$?
    Answer: The price level rises and real GDP rises. An open-market purchase pays for bonds with new reserves, increasing the money supply, lowering interest rates and stimulating interest-sensitive spending, which shifts AD rightward from AD₁. A rightward shift of AD crosses the upward-sloping SRAS curve up and to the right of E₁, so the new short-run equilibrium has both a higher price level and higher real GDP. This exemplifies expansionary monetary policy's short-run effects—increased money supply boosts spending and output while causing some inflation. A common error is assuming monetary policy affects only prices or only output, but in the short run, both change. The key insight is that rightward AD shifts (from any expansionary policy) create movements up along SRAS, raising both price level and real GDP.
16. Starting from equilibrium $E_1$ in the AD–AS model shown, aggregate demand shifts left from AD$_1$ while SRAS remains unchanged. Which of the following best describes the short-run change in the price level and real GDP?
    Answer: The price level falls and real GDP falls from their initial equilibrium values. A leftward shift of aggregate demand with SRAS unchanged means less spending at every price level, so the economy slides down along SRAS from E1 to a new short-run equilibrium below and to the left of it. This contraction brings a lower price level (PL) and lower real GDP (Y) because decreased demand reduces both pricing power and output. The PL falls with slack in the economy, and Y declines as spending cuts ripple through production. For analysis, first identify the shifting curve—AD left from demand reducers—and compare the new equilibrium to the initial one.
17. Based on the AD–AS model shown, suppose a sharp increase in oil prices raises firms' production costs, shifting short-run aggregate supply in the short run. Compared with $E_1$, which outcome occurs at the new short-run equilibrium?
    Answer: The price level rises and real GDP falls. A sharp jump in oil prices is a negative supply shock: energy is an input almost every firm uses, so higher oil prices mean firms supply less real output at every price level and SRAS shifts leftward from SRAS₁. A leftward shift of SRAS crosses the unchanged AD curve up and to the left of E₁, so the new short-run equilibrium has a higher price level but lower real GDP. This demonstrates cost-push inflation—rising costs push prices up while reducing output, creating stagflation. Students often mistakenly think all inflation increases output, but cost-push inflation uniquely combines higher prices with lower output. The strategy is to recognize that when SRAS shifts left due to higher costs, the economy moves up along the AD curve to a point with higher prices and lower output.
18. Starting from equilibrium $E_1$ in the AD–AS model shown, government increases purchases of goods and services, shifting aggregate demand in the short run. Which statement correctly identifies the type of change and its effects?
    Answer: Demand-pull; the price level rises and real GDP rises. Government purchases are a direct component of aggregate demand (C + I + G + NX), so an increase in them raises spending at every price level and shifts AD to the right of AD₁. A rightward shift of AD crosses the unchanged SRAS curve up and to the right of E₁, so the new short-run equilibrium has both a higher price level and higher real GDP—this is called demand-pull inflation because increased demand pulls prices upward. This exemplifies expansionary fiscal policy's short-run effects on the economy. A common misconception is confusing demand-pull with cost-push changes; demand-pull always involves AD shifting and creates positive correlation between prices and output. The diagnostic strategy is to identify the initial shift (here, AD right from fiscal expansion) and trace the new equilibrium along the other curve.
19. Based on the AD–AS model shown, suppose the government increases spending, which shifts aggregate demand. In the short run, which of the following best describes the movement from E1 to the new short-run equilibrium?
    Answer: The price level increases and real GDP increases in the short run. Fiscal expansion works through aggregate demand: government spending is one of its components, so an increase in government spending shifts the AD curve rightward from AD1. A rightward shift of AD crosses SRAS up and to the right of E1, so at the new short-run equilibrium both the price level and real GDP increase. A common error is thinking that only output changes with fiscal policy, but the upward-sloping SRAS means that increased demand raises both prices and output. The key analytical approach is recognizing that rightward AD shifts (from expansionary policies) always move the economy up along the SRAS curve, increasing both variables.
20. Based on the AD–AS model shown, a technological improvement increases productivity, shifting short-run aggregate supply rightward from $SRAS_1$ in the short run. Starting from $E_1$, which outcome occurs at the new short-run equilibrium?
    Answer: The price level falls and real GDP rises. Better technology lets firms get more output from the same workers and machines, which lowers per-unit costs and shifts SRAS rightward from SRAS₁. The new SRAS crosses the unchanged AD curve down and to the right of E₁, so the new short-run equilibrium has a lower price level but higher real GDP. This represents the ideal scenario of technology-driven growth—more output with lower prices, benefiting consumers through both increased availability and affordability. Students often mistakenly assume all supply shifts are negative, but positive supply shocks like productivity gains shift SRAS right. The key insight is that rightward SRAS shifts (from any efficiency gain) create movement down along the AD curve, lowering prices while expanding output.

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