ECO12M2: Economics 1B Study Guide (South Africa)

Economics 1B (often aligned with Introductory Macroeconomics and core economic principles at South African universities/colleges/TVETs) typically builds on basic supply–demand and production ideas to explain national output, inflation, unemployment, the money market, and government and external sector roles. This study guide is designed to help you master the kind of exam questions that recur across South African teaching institutions: problem-solving with models, interpreting diagrams and graphs, applying definitions accurately, and writing coherent explanations using economics language.

Because ECO12M2 course content can vary slightly by institution, this guide focuses on the core macroeconomic toolkit that appears in Economics 1B modules nationwide, while also showing how to present answers in ways that match marking rubrics (especially: correct assumptions, correct model choice, and consistent interpretation).

Economics 1B: Core Macroeconomic Concepts, Measurement, and Data in the South African Context

Macroeconomics studies the economy as a whole—total output (GDP), overall price level (inflation), employment and unemployment, and how these outcomes interact with monetary policy, fiscal policy, and external trade. In Economics 1B, you’re usually expected to know the definitions, understand the logic behind the models, and be able to compute and interpret simple measures.

1) GDP and National Income Accounting: From Definitions to Exam Computations

In most ECO12M2-style assessments, GDP is a central starting point. You should be able to state clearly what GDP measures and how different approaches relate.

Key definitions (memorise and use precisely):

• Gross Domestic Product (GDP): the market value of all final goods and services produced within a country’s borders in a given period (usually a year or quarter).
• Final goods vs intermediate goods:
  • Final goods are bought by end users.
  • Intermediate goods are used as inputs for production.
• Nominal GDP vs Real GDP:
  • Nominal GDP values output at current-year prices.
  • Real GDP adjusts for inflation using a base-year price level.
• GDP growth rate: often expressed as the percent change in real GDP over time.

What examiners look for:

1. You correctly identify that GDP counts final production only.
2. You distinguish nominal and real GDP (and explain why inflation can “inflate” nominal GDP without real growth).
3. You can compute simple growth rates from real GDP figures.

Example: GDP growth computation (typical exam format)

Suppose:

• Real GDP in 2022 = R1 200 billion
• Real GDP in 2023 = R1 260 billion

Then the real GDP growth rate is:
[
\frac{1,260 – 1,200}{1,200}\times 100 = \frac{60}{1,200}\times 100 = 5%
]

In an exam answer, you’d write:

• “Real GDP increased from R1 200 billion to R1 260 billion.”
• “Growth rate = 5%.”
• “This indicates an increase in real output, not just a price rise.”

2) Inflation and the Price Level: CPI, GDP Deflators, and Interpreting Results

Inflation is usually measured through price indices such as:

• CPI (Consumer Price Index): tracks the price of a “basket” of consumer goods and services.
• GDP deflator: derived from the ratio of nominal GDP to real GDP.

Core understanding:

• Inflation is an increase in the general price level.
• High inflation can reduce purchasing power, distort decisions, and affect interest rates.

Exam-style calculation: inflation rate

If CPI:

• CPI in year 1 = 150
• CPI in year 2 = 165

Then inflation rate:
[
\frac{165 – 150}{150}\times 100 = \frac{15}{150}\times 100 = 10%
]

Interpretation in economics language:

• “A 10% inflation rate means the average cost of the CPI basket rose by 10%.”
• “This reduces real income if wages don’t rise at the same pace.”

3) Unemployment and Labour Market Indicators

You may also need to describe unemployment and interpret rates. Key terms:

• Labour force: those willing and able to work (employed + unemployed).
• Unemployment rate: unemployed / labour force × 100.
• Types of unemployment:
  • Frictional: people between jobs.
  • Structural: mismatch between skills and job requirements.
  • Cyclical: linked to downturns in aggregate demand.

In many South African contexts, unemployment discussions often link to:

• skills mismatch,
• youth labour market challenges,
• informality and underemployment,
• structural barriers.

Exam tip: If asked to “explain causes of unemployment,” you should distinguish demand-side causes (low aggregate demand) from supply-side causes (skills mismatch, wage rigidity, institutional factors).

Mini-case (South Africa-style reasoning)

If a recession reduces firms’ sales, firms may reduce production and layoffs rise → unemployment rises.
If industries require skills that unemployed workers don’t have, even when demand improves, unemployment may persist due to structural mismatch.

4) The Production and Income Flows: Circular Flow and Real vs Money Variables

Economics 1B commonly introduces:

• the circular flow of income and expenditure,
• distinction between real variables (output, employment, real wages) and nominal variables (prices, nominal wages).

A strong answer explains why macroeconomics must consider both:

• real production,
• money and prices.

For example:

• In the short run, output fluctuations relate strongly to aggregate demand.
• In the longer run, inflation and growth relate to productivity, resources, and price expectations.

Institution Cluster: University of Johannesburg (UJ) — Economics 1B / ECO12M2-typed Content

This cluster focuses on how Economics 1B-style macro questions are typically structured within South African university teaching (including UJ and comparable departments), especially when students use models like aggregate demand (AD), aggregate supply (AS), and output-expenditure frameworks.

Note on institutional specificity: While course codes and exact lecture outlines may differ by year, this cluster provides exam-prepared answer patterns aligned with common UJ macro teaching practices (clear diagram logic, consistent model assumptions, and explicit definitions).

1) How UJ-type macro questions are marked

Examiners commonly reward:

• diagram correctness (axes, shifts, intercepts),
• economic explanation (why a curve shifts, not just that it shifts),
• linking variable changes (e.g., interest rate → investment → AD → output).

2) Typical question formats and high-scoring structure

A good exam response often follows:

1. Define the macro concept (e.g., inflation; equilibrium output).
2. State assumptions (e.g., short-run sticky prices; ceteris paribus).
3. Use the model (AD–AS, Keynesian cross).
4. Explain direction of change (increase/decrease).
5. Conclude with what happens to output, employment, and prices.

3) Worked logic example: Interest rate changes

Suppose the central bank reduces policy rates (lower interest rates).

• Lower interest rates reduce the cost of borrowing.
• Investment tends to rise (more projects become profitable).
• Higher investment increases aggregate demand.
• In the short run, output increases (employment rises, unemployment falls).

In a diagram:

• AD shifts right (if using AD–AS).
• Equilibrium moves to higher output and higher price level (short-run effect).

Counter-point to include if asked about complexities:

• If households and firms are pessimistic, investment may not respond much despite low interest rates.
• If banks’ lending standards tighten, transmission weakens.

This “include a nuance” habit often upgrades your marks from “correct” to “excellent.”

Aggregate Demand, the Keynesian Cross, and Short-Run Equilibrium: Output, Multipliers, and Policy

The heart of many Economics 1B syllabi is the short-run determination of output, where economic activity depends on aggregate demand for goods and services. You should be able to compute equilibrium output and interpret how changes in spending components shift equilibrium.

1) The Keynesian Cross: Consumption, Investment, and Equilibrium Output

A common framework is the Keynesian cross, where equilibrium output occurs when:
[
Y = AE
]
where:

• (Y) = aggregate income/output,
• (AE) = planned aggregate expenditure (consumption + investment + government spending + net exports, depending on the version used).

Consumption function

A standard consumption function is:
[
C = a + bY
]

• (a) = autonomous consumption (consumption when income is zero).
• (b) = marginal propensity to consume (MPC), where (0 < b < 1).

Aggregate expenditure

In a simplified closed economy (no net exports):
[
AE = C + I + G
]
So:
[
AE = a + bY + I + G
]

Equilibrium:
[
Y = a + bY + I + G
]
Solve:
[
Y – bY = a + I + G
]
[
(1-b)Y = a + I + G
]
[
Y = \frac{1}{1-b}(a + I + G)
]

The term:
[
\frac{1}{1-b}
]
is the multiplier, showing how much equilibrium output changes when autonomous spending changes.

2) The Multiplier: Interpreting the Math into Real Economic Meaning

Why multipliers happen:

• An initial increase in spending increases income.
• Higher income increases consumption.
• That extra consumption is part of further spending, raising income again.

The process continues, diminishing each round because MPC < 1.

Example multiplier computation

If:

• (MPC = 0.75) then (1 – b = 0.25)
• Multiplier = (1 / 0.25 = 4)

So an increase in autonomous government spending of R10 billion leads to:

• Output increase = (4 \times 10 = R40) billion (in the simplified model)

Important exam nuance: In the real economy, leakage occurs:

• saving (MPS = 1 − MPC),
• taxes,
• imports (in open economy models).
  Those reduce the size of the multiplier relative to the simplest closed economy version.

3) Policy: Fiscal Multipliers and “Crowding Out” Risk

Fiscal policy in the Keynesian cross

If government spending (G) increases:

• AE shifts up.
• Equilibrium output rises by multiplier × change in autonomous spending.

Crowding out (often mentioned in higher-level macro, but can appear in intro questions)

Crowding out can happen if:

• higher government spending increases interest rates (in models with financial markets),
• or if wages/prices rise enough that real output doesn’t increase as much.

In Econ 1B, you might be asked to explain:

• “Why fiscal policy may or may not be effective.”

A high-scoring answer includes:

• In the Keynesian (short-run) logic, fiscal policy works through demand.
• But if the economy is near full capacity or if interest rates rise, output response may be limited.

4) Investment Function and Interest Rates (Intro level)

Even if the formal investment function is not always required, you often need to link:

• interest rates → cost of capital → investment spending → AD → output.

Common exam statement

• “Lower interest rates raise investment because borrowing becomes cheaper.”

Counter-argument you can add

• Investment depends on expectations of future demand and risk.
• If firms expect low future sales, they may not invest even if interest rates fall.

Institution Cluster: University of Cape Town (UCT) — Economics 1B-Style Macro Answering

This cluster focuses on the style of reasoning expected at research-led universities like UCT: precise definitions, disciplined diagram work, and evidence-based interpretation of policy effects.

1) Diagram discipline: shifts vs movements

A major marking theme is distinguishing:

• movement along a curve (variable changes while other factors fixed),
• shift of a curve (change in a determinant).

In a Keynesian cross:

• If MPC or autonomous spending changes, AE shifts.
• If income changes, you move along the AE line.

2) Example: increase in autonomous consumption

If (a) rises (autonomous consumption increases):

• (AE) shifts upward.
• Output increases by multiplier × Δa.

In terms of writing:

1. “Autonomous consumption increases planned expenditure at every level of income.”
2. “Aggregate expenditure curve shifts upward.”
3. “Equilibrium output rises.”

Then:

• If asked for numerical result, compute:
  [
  \Delta Y = \text{Multiplier} \times \Delta \text{Autonomous spending}
  ]

3) “Explain in words” style

If you’re asked: “Explain how a cut in taxes affects output,” a good UCT-type answer uses:

• Tax cut → disposable income rises → consumption rises (via MPC) → AE rises → output rises.
  Then add limitations:
• If households save more (lower MPC response), consumption rise is smaller.
• If tax cut doesn’t increase disposable income effectively (e.g., expectations of future tax hikes), effect can weaken.

AD–AS, Inflation, Unemployment, and the Macroeconomic Policy Trade-offs

Once equilibrium output and demand logic are clear, Economics 1B typically moves toward the relationships between:

• output and unemployment (business cycle),
• inflation and price adjustment,
• aggregate demand and aggregate supply intersections.

Even if your module doesn’t deeply cover Phillips curve history, you should understand the intuitive trade-off: inflation can move with conditions in output and unemployment markets.

1) Aggregate Demand (AD): What it Means and Why it Slopes

In a simple AD–AS approach:

• AD shows the relationship between the price level (P) and aggregate output (Y).
• It’s often downward sloping because when prices are lower:
  • real money balances rise (central bank controls nominal money),
  • interest rates may fall,
  • investment rises,
  • thus demand rises.

Even if you do not use full money-market derivations, exam answers often require the “logic chain”:

• lower price level → higher real balances → lower real interest rate → higher planned spending → higher output.

2) Aggregate Supply (AS): Short Run vs Long Run

A standard macro model uses:

• Short-run aggregate supply (SRAS): typically upward sloping if wages and prices are sticky in the short run.
• Long-run aggregate supply (LRAS): vertical at potential output (full employment output).

Short-run intuition

If demand rises:

• firms see higher prices relative to costs,
• they produce more,
• output rises (in short run).

If demand falls:

• firms reduce output.

Long-run intuition

In the long run, output returns to potential, though the price level may adjust.

3) Graph Interpretation: Common Exam Questions

You’ll often be asked: “What happens to output and price level if government spending increases?” You should specify:

• AD shift,
• movement along SRAS,
• final changes.

Example: Government spending increases

• Fiscal expansion increases autonomous spending → AD shifts right.
• In the short run:
  • output rises,
  • inflation/price level rises.
• In the long run:
  • output returns to potential,
  • price level stays higher if inflation persists.

If the exam includes unemployment:

• Higher output reduces unemployment in the short run (cyclical unemployment declines).

4) Unemployment and the Business Cycle

In intro macro, unemployment changes are often linked to:

• demand shortfalls: recession → lower output → layoffs → unemployment rises.
• recovery: output rises → unemployment falls.

But: unemployment is not only cyclical. Structural and frictional components remain.

A high-quality answer distinguishes:

• Cyclical unemployment: varies with demand.
• Structural unemployment: persists due to mismatch.
• Frictional unemployment: transitions between jobs.

5) Inflation Dynamics: Why Inflation Doesn’t Always Fall Automatically

A common conceptual question:

• “Why doesn’t inflation instantly fall when demand slows?”
  Possible answers:
• contracts and sticky wages,
• expectations,
• menu costs,
• the lag between policy changes and real economic activity.

Your answer can include:

1. Short-run rigidity keeps prices from adjusting immediately.
2. Firms set prices gradually, not instantly.
3. If expectations remain high, inflation can be sticky.

6) Policy Trade-offs: Expansionary vs Contractionary Policy

Expansionary policy (e.g., increased G or lower taxes)

• Raises AD.
• In short run: higher output, lower unemployment, higher inflation.
• In long run: output returns to potential; inflation may remain higher.

Contractionary policy (e.g., reduced G or tax increases)

• Lowers AD.
• Short run: lower output, higher unemployment, lower inflation.
• Long run: output returns to potential; price level lower.

Exam “policy trade-off” writing

A typical marking guide expects you to:

• mention the direction of output/unemployment and inflation,
• mention short-run vs long-run differences,
• mention that the economy may not move exactly like the model if shocks occur.

Institution Cluster: Stellenbosch University (SU) — Economics 1B with Emphasis on Analytical Justification

This cluster focuses on the expectation that students provide analytical justification, not only diagram outcomes. In many SU-style assessments, a correct diagram alone is insufficient—you must also explain the mechanism.

1) How to structure a policy impact answer

A disciplined SU-style paragraph might follow:

• “Policy X changes determinant Y, which shifts curve Z.”
• “The intersection changes equilibrium Y and P.”
• “Because short-run prices/wages are sticky, output deviates from potential.”
• “In the long run, output returns to potential while prices adjust.”

2) Mechanism language you can reuse

• “Aggregate demand rises because planned spending increases.”
• “Higher expected profitability increases planned investment (if the interest rate or expected sales improve).”
• “In the short run, firms respond to higher demand by increasing output rather than fully adjusting prices immediately.”

3) Adding South African interpretive examples

When contextualising, you can mention:

• volatile electricity supply affecting production capacity (affecting AS),
• exchange rate volatility affecting import prices (affecting inflation),
• fiscal constraints affecting ability to stimulate demand.

Be careful: if you introduce a specific policy name or number, it must be consistent and accurate. If not sure, keep it general (e.g., “import prices rise when the rand weakens,” without giving an unverified percent).

Monetary Policy, Money, Interest Rates, and Financial Transmission (Intro Level)

Economics 1B frequently includes monetary policy fundamentals even when students are not expected to master advanced models. The key is understanding:

• what “money” does,
• how central bank policy affects interest rates,
• how interest rates affect consumption and investment,
• and why the transmission mechanism can fail.

1) Money and the Financial System: What “Money” Means in Macro

Money typically includes:

• currency (notes and coins),
• demand deposits (bank deposits accessible through transactions).

Functions of money:

• medium of exchange,
• unit of account,
• store of value.

An exam question might ask why money matters:

• because it affects real balances and interest rates, influencing spending.

2) The Interest Rate as the Transmission Channel

A simplified transmission mechanism:

1. Central bank changes the policy rate (or liquidity conditions).
2. Market interest rates change.
3. Borrowing costs change.
4. Investment and interest-sensitive consumption change.
5. Aggregate demand changes.
6. Output and inflation respond.

Key vocabulary

• policy rate: the rate used by the central bank.
• real interest rate: nominal interest rate minus expected inflation (intro level).
• credit constraints: if borrowers cannot obtain loans, interest rate cuts may not increase spending.

3) Liquidity, Money Supply, and Short-Run Effects

In many intro modules, you may see:

• money supply changes shift money market equilibrium.
  Even when not fully calculated, you should know the intuition:
• If money supply increases, interest rates tend to fall (with liquidity preference assumptions).
• Lower interest rates stimulate spending.

4) Monetary Policy Effectiveness: Reasons It May Be Weak

A key exam skill: presenting both sides of the policy effectiveness story.

Reasons transmission can weaken:

• Banking sector risk aversion → banks may not lend even when rates fall.
• Households may be highly indebted → lower rates reduce interest costs, but households may still cut consumption if they focus on debt repayment.
• Economic uncertainty → firms delay investment regardless of low interest rates.

A good exam response explicitly states:

• “In the standard model, lower interest rates increase investment.”
• “However, if credit constraints or weak expectations exist, the effect on AD may be smaller.”

5) Inflation and Monetary Policy: Avoiding the “One-to-one” Trap

An intro macro misunderstanding is thinking:

• “If the central bank tightens, inflation falls instantly and proportionally.”

A more accurate explanation:

• Monetary policy affects demand and expectations with lags.
• Inflation depends not only on demand but also on supply shocks.

For example (conceptual, not numeric):

• if there is an oil shock raising production costs, inflation may rise even when demand is weak.

Institution Cluster: University of Pretoria (UP) — Economics 1B Monetary-Fiscal Integration

This cluster emphasises integrating monetary and fiscal policy arguments in a consistent macro model. UP-type marking often rewards students who connect policy tools to outcomes through multiple links.

1) Combined policy question template

If asked: “How would monetary policy and fiscal policy affect output and inflation?”:

• Start with each policy’s AD effect.
• Add interest rate and spending channel for monetary policy.
• Mention crowding out or interest rate change effects if relevant.
• Finish with short-run vs long-run interpretation.

2) Example integrated reasoning (words + model link)

• “Expansionary fiscal policy increases government spending, directly raising AD.”
• “Expansionary monetary policy reduces interest rates, raising investment, further increasing AD.”
• “In the short run, output increases and inflation rises.”
• “Over time, if the economy approaches potential output, output returns to potential; inflation remains influenced by the aggregate price level adjustments and expectations.”

3) Counter-argument to score marks

• “If fiscal expansion leads to higher interest rates through financial markets, monetary expansion could be offset.”
• “If supply shocks occur, AD policies might not reduce inflation effectively.”

Exam Preparation Blueprint: How to Solve ECO12M2 Economics 1B Problems Efficiently (Diagrams, Computations, and Written Answers)

This section is about exam technique—but specifically tailored to the types of marks you lose if you don’t format economic reasoning correctly. Economics 1B exams often reward method and clarity as much as the final numerical answer.

1) The “Model Choice” Checklist

Before solving, ask:

1. Is the question about GDP / inflation / unemployment measurement?
   → Use definitions and indices; compute growth or rates.
2. Is it about equilibrium output in the short run?
   → Use Keynesian cross / expenditure model and multipliers.
3. Is it about price level and output together?
   → Use AD–AS diagram logic.
4. Is it about policy effects through interest rates?
   → Use monetary transmission logic.

Common mistake: Using the AD–AS model to answer a question that only tests multiplier logic. Conversely, using only Keynesian cross when the question explicitly asks about inflation response and price level shifts.

2) Diagram Rules That Usually Determine Half Your Marks

For any AD–AS diagram:

• Label axes correctly: price level on vertical, output on horizontal.
• Mark the direction of each curve:
  • AD downward sloping (typical).
  • SRAS upward sloping.
  • LRAS vertical at potential output.
• When policy changes:
  • show curve shift (AD shift left/right).
• Show the new equilibrium point.

For Keynesian cross:

• Horizontal axis: income/output (Y).
• Vertical axis: expenditure (AE).
• Draw:
  • 45-degree line (AE=Y),
  • AE line intercept and slope (based on MPC).
• Equilibrium is where AE intersects the 45-degree line.

Rubric-friendly writing next to diagrams:

• “AE shifts upward because autonomous spending rises.”
• “New equilibrium occurs at higher Y (output).”

3) Written Explanation: The Three-Part Answer Formula

Use this structure repeatedly:

1. Mechanism: What changes? Through which channel?
2. Model outcome: What happens to output/price/inflation/unemployment in the model?
3. Time horizon: short run vs long run.

Example: Government spending increase (written answer)

• Mechanism: “An increase in government spending raises autonomous spending and planned aggregate expenditure.”
• Model outcome: “In the Keynesian cross, the AE line shifts upward; equilibrium output increases.”
• Time horizon: “In the short run, output can rise above potential, but in the long run output returns to potential while the price level adjusts upward.”

4) Numerical Problem Strategy: Keep Units and Round Consistently

When computing:

• GDP growth rates, inflation rates, multipliers, equilibrium output.

Rules:

1. Ensure the variable you’re computing is dimensionless (percent rates) when required.
2. If output is in billions of rand, keep it consistent.
3. Round at the end unless the exam instructions specify otherwise.

Example: equilibrium output using multiplier

Suppose:

• (MPC = 0.8) → multiplier = (1/(1-0.8)=5)
• Autonomous spending (A_0 = 200) (billions)
  Then:
  [
  Y = 5 \times 200 = 1,000
  ]
  In exam writing:
• “Multiplier = 5 because MPC = 0.8.”
• “Equilibrium output = 5 × autonomous spending = 1,000 billion.”

5) Common Exam Traps (and how to avoid them)

1. Confusing nominal and real GDP:
   Nominal changes can reflect prices, not production.
2. Forgetting “final goods” in GDP:
   Counting intermediate goods double-counts.
3. Using MPC when you should use MPS:
   Multiplier uses (1/(1-MPC)). Since MPS = 1 − MPC, both can be used correctly but must be consistent.
4. Wrong direction of shifts:
   For example, inflation reduction policies shift AD left; output decreases.
5. Stating conclusions without mechanism:
   “Output will rise” is weaker than “Output rises because planned expenditure increases via the MPC and multiplier.”

Institution Cluster: TVETs (e.g., Hospitality/Business-leaning Colleges with Economics Components) — Practical Problem-Solving Approach

TVET Economics modules sometimes emphasise application, not heavy derivations. Your goal is to:

• master definitions,
• interpret graphs,
• do straightforward computations carefully,
• and explain in simpler language.

1) A simplified answer style that still earns marks

• Define key terms first.
• State the direction of effect.
• Provide one short explanation.
• If calculations are required, show steps clearly.

2) Example: unemployment rate question

If asked: “Unemployment rate rises,” you can respond:

• “Unemployment rate = unemployed ÷ labour force × 100.”
• “If unemployment increases faster than the labour force, unemployment rate rises.”
• “In a recession, demand falls, leading firms to reduce hiring.”

Even without complex macro models, this is correct and marks well when supported by definitions.

Consolidated Study Pack: Definitions, Formulas, and Quick Reference

This section consolidates key items you should keep revising. It is not filler: these are the exact “building blocks” you use across most ECO12M2 questions.

1) Definitions (high-yield)

• GDP: value of final goods and services produced within borders.
• Real GDP: GDP adjusted for price changes.
• Nominal GDP: GDP valued at current prices.
• Inflation: sustained increase in general price level.
• CPI: consumer price index tracking a consumer basket.
• Unemployment rate: unemployed ÷ labour force × 100.
• Aggregate demand (AD): total planned spending on domestic output at different price levels.
• Aggregate supply (AS): total production firms are willing and able to supply at different price levels.
• Potential output (Y*): output consistent with full employment in the long run.

2) Core formulas

• GDP growth rate:
  [
  g = \frac{Y_{t} – Y_{t-1}}{Y_{t-1}}\times 100
  ]
• Inflation rate (using CPI):
  [
  \pi = \frac{CPI_t – CPI_{t-1}}{CPI_{t-1}}\times 100
  ]
• Consumption function:
  [
  C = a + bY
  ]
• Multiplier (simple Keynesian cross):
  [
  k = \frac{1}{1-b}
  ]
  where (b = MPC).

3) Quick model outcomes (use as exam memory anchors)

• Right shift of AD (increase in spending):
  Short run: (Y↑), (P↑).
  Long run: (Y) returns to potential; (P) remains higher.
• Left shift of AD (decrease in spending):
  Short run: (Y↓), (P↓).
  Long run: (Y) returns to potential; (P) lower.
• Increase in SRAS (positive supply shock):
  Output higher, price level lower (short run), with long-run output returning to potential.

Practice Set (Structured Like Exam Questions)

The following practice set is designed to simulate the typical ECO12M2 “mix” of definitions, computations, diagram reasoning, and policy explanation. Use it to test whether you can produce full-credit answers under time pressure.

Question 1: Real vs Nominal GDP

A country’s nominal GDP increased from R800 billion to R880 billion in one year. CPI increased from 100 to 110.

1. Calculate inflation rate.
2. Explain whether nominal GDP growth implies real growth.

What you should do:

• (1) Inflation = (110 − 100)/100 × 100 = 10%.
• (2) Discuss that nominal growth was 10% too, so real growth might be zero (conceptually). A full real GDP calculation would need base-year method, but you can interpret the relationship.

Question 2: Keynesian cross equilibrium

Let consumption be:
[
C = 50 + 0.8Y
]
Investment (I = 40) and government spending (G = 30). Consider a closed economy (ignore net exports).

1. Write the equilibrium condition (Y = AE).
2. Compute equilibrium output (Y).

Solution steps:

• (AE = C + I + G = (50 + 0.8Y) + 40 + 30 = 120 + 0.8Y).
• Equilibrium: (Y = 120 + 0.8Y).
• (0.2Y = 120) → (Y = 600).

Question 3: Multiplier effect

In Question 2, suppose government spending increases from R30 to R40.

1. Compute the change in autonomous spending.
2. Compute change in equilibrium output.

Key:

• (MPC = 0.8) → multiplier = 1/(1−0.8)=5.
• ΔG = 10.
• ΔY = 5 × 10 = 50.

So new output = 600 + 50 = 650 (in the model).

Question 4: AD–AS policy reasoning (no heavy math)

Suppose an expansionary fiscal policy increases AD.

1. Describe the short-run impact on output and price level.
2. Describe the long-run impact on output.

What you should say:

• Short run: AD shifts right; output rises; price level rises.
• Long run: output returns to potential; price level remains higher.

Question 5: Monetary transmission and limitations

A central bank reduces policy interest rates.

1. Explain the standard transmission channel to aggregate demand.
2. Give two reasons why the effect on output might be weaker than expected.

Two reasons (acceptable):

• credit constraints / banks reduce lending,
• weak expectations → low investment despite lower rates,
• high household debt causing caution,
• supply shocks limiting production capacity.

Final Review Strategy: How to Use This Guide for ECO12M2 Success

To perform well in Economics 1B, focus on building “automaticity” with:

1. Definitions (so you can write fast and correctly),
2. Core models (Keynesian cross; AD–AS; unemployment–output logic),
3. Diagrams (axes, direction of shift, equilibrium interpretation),
4. Computations (growth rates, inflation, multiplier, equilibrium output).

A strong study workflow:

• Step 1 (Day 1–2): Learn the definitions and formulas; do 5–10 short computations.
• Step 2 (Day 3–4): Practice full model answers: one Keynesian cross question, one AD–AS policy question, one unemployment/inflation interpretation.
• Step 3 (Day 5): Do a timed mixed set (5 questions), then review where marks were lost.
• Step 4 (Ongoing): Rewrite “top” answers: especially diagram explanations and policy mechanisms.

If you master the mechanism and consistency—curve shifts, correct multipliers, correct time horizons—you’ll be positioned to score strongly even when questions are phrased in unfamiliar ways.

End of ECO12M2 Economics 1B Study Guide