ECN2AB2: Intermediate Microeconomics & Macroeconomics Course Notes (South African HE/TVET Focus)

Intermediate Microeconomics & Macroeconomics (commonly coded as ECN2AB2 in South African university syllabi) sits at the intersection of two core tasks that every applied economist must master: explaining individual and firm behaviour (microeconomics) and understanding the behaviour of the economy as a whole (macroeconomics). These notes provide an exam-ready, concept-driven guide to the typical content covered in an intermediate course: consumer and producer choice, market structures, general equilibrium and welfare, and core macro models involving output, inflation, interest rates, unemployment, and open-economy linkages. Throughout, examples and study strategies are tailored to the South African context—while keeping the theory universal—so that you can connect diagrams, calculations, and policy discussions to what you are likely to be assessed on.

Section 1: Microeconomics Foundations—Demand, Utility, Choice, and Market Outcomes

Microeconomics begins with choice under constraints. At intermediate level, you are expected to move beyond definitions into mechanism: how preferences translate into demand, how firms translate technology into supply, and how equilibrium emerges when markets clear.

Subsection 1.1 Demand, Preferences, and Utility Maximisation

A standard starting point is the consumer who maximises utility subject to a budget constraint. Suppose consumer utility is represented by (U(x,y)) where (x) and (y) are goods. The budget constraint is:

[
p_x x + p_y y = m
]

where (p_x) and (p_y) are prices and (m) is income (often called “money income”).

Key exam skills:

1. Draw the budget line: intercepts at (x = m/p_x) and (y = m/p_y).
2. Use intuition (and sometimes formal derivatives) to find the optimal bundle where indifference curves are tangent to the budget line.
3. Explain how demand changes when:
   • income changes (income effects),
   • the price of one good changes (substitution and income effects).

Example: Two-goods demand response

Let income be (m = 1,000). Suppose (p_x = 50), (p_y = 100).

• Budget line: (50x + 100y = 1,000).
• Intercepts: (x = 20) (when (y=0)), (y = 10) (when (x=0)).

If (p_x) falls to (25) (holding everything else constant), the new budget constraint is:

[
25x + 100y = 1,000
]

Now intercepts become (x = 40) and (y=10). The line pivots outward around the (y)-intercept.

What examiners look for: a clear explanation that the pivot changes relative affordability, shifting consumption choices.

Subsection 1.2 Indifference Curves, MRTS, and the Tangency Condition

If utility is smooth, the tangency condition is often expressed using the marginal rate of technical substitution in consumption (MRTS), which equals the ratio of prices.

For goods (x) and (y):

[
\text{MRTS}_{xy} = \frac{MU_x}{MU_y} = \frac{p_x}{p_y}
]

where (MU_x = \frac{\partial U}{\partial x}) and similarly for (MU_y).

Concrete illustration with a utility function

Assume:

[
U(x,y) = x^{0.5}y^{0.5}
]

This is Cobb–Douglas with equal exponents. Then:

[
MU_x \propto x^{-0.5}y^{0.5}, \quad MU_y \propto x^{0.5}y^{-0.5}
]

So:

[
\frac{MU_x}{MU_y} = \frac{y}{x}
]

Tangency gives:

[
\frac{y}{x} = \frac{p_x}{p_y} \Rightarrow y = x\frac{p_x}{p_y}
]

Substitute into budget:

[
p_x x + p_y\left(x\frac{p_x}{p_y}\right) = m
\Rightarrow p_x x + p_x x = m
\Rightarrow 2p_x x = m
\Rightarrow x = \frac{m}{2p_x}
]

Similarly:

[
y = \frac{m}{2p_y}
]

This yields the classic Cobb–Douglas demand shares: each good takes a constant proportion (here 50%) of income.

Why this matters in exams: It enables quick derivation of demand functions and budget share interpretations.

Subsection 1.3 From Utility to Individual Demand and Market Demand

Individual demand (x(p_x,p_y,m)) aggregates to market demand by summing across consumers (or adding quantities if demands are given by market segments). If there are (N) identical consumers each demanding (x(p_x)), then market demand is (X(p_x)=N x(p_x)).

Example: Market demand with fixed number of buyers

Suppose each consumer’s demand for a good is (x(p)=\frac{m}{2p}). If (m=1,000) and (N=100) consumers:

[
X(p)=100\cdot \frac{1,000}{2p} = \frac{50,000}{p}
]

If (p=100), then (X=500). If (p=50), then (X=1,000).

This supports typical exam tasks:

• compute equilibrium price when supply is known,
• evaluate effects of taxes or price controls.

Subsection 1.4 Elasticity—Price, Income, and Cross Effects

Elasticity captures responsiveness. The price elasticity of demand is:

[
\epsilon_{d}=\frac{\Delta Q/Q}{\Delta P/P}
]

At intermediate level, you should distinguish:

• point elasticity vs arc elasticity,
• elastic vs inelastic demand,
• income elasticity ( \epsilon_i ),
• cross-price elasticity ( \epsilon_{xy} ).

Quick elasticity interpretation

• If ( \epsilon_d > 1): demand is elastic.
• If ( \epsilon_d < 1): demand is inelastic.
• If ( \epsilon_{xy} > 0): goods (x) and (y) are substitutes.
• If ( \epsilon_{xy} < 0): they are complements.

Subsection 1.5 Producer Theory—Cost, Technology, and Supply

Firms convert inputs into outputs using technology. A production function might be:

[
q=f(L,K)
]

where (L) is labour and (K) is capital. In short-run analysis, one input may be fixed (e.g., (K) fixed). Intermediate micro often requires:

• deriving labour demand from profit maximisation,
• discussing marginal product, marginal cost, and diminishing returns.

Cost relationships

Key definitions:

• Total cost (C(q))
• Average cost (AC = C/q)
• Marginal cost (MC = dC/dq)

In competitive markets:

• Supply is linked to marginal cost: firm produces where (p=MC) (subject to shutdown conditions).

Subsection 1.6 Market Equilibrium and Comparative Statics

A competitive market equilibrium satisfies:

• demand equals supply (Q_d(P)=Q_s(P)).

Then comparative statics: what happens to (P) and (Q) if demand shifts (income changes, preferences change) or supply shifts (technology, input prices change).

Example: Equilibrium with linear functions

Let:
[
Q_d = 100 – 2P,\quad Q_s = 20 + 3P
]
Set equal:
[
100 – 2P = 20 + 3P
\Rightarrow 80 = 5P
\Rightarrow P^* = 16
]
Then:
[
Q^* = 100 – 2(16)=68
]

If a supply shock reduces supply by 10 units at every price:
[
Q_s' = 10 + 3P
]
New equilibrium:
[
100-2P = 10+3P
\Rightarrow 90=5P
\Rightarrow P'=18
]
[
Q'=100-2(18)=64
]

What to write in an exam response: supply reduction increases price and reduces quantity.

Subsection 1.7 Welfare Analysis—Surplus, Deadweight Loss, and Transfers

Welfare analysis uses:

• consumer surplus (area under demand above price),
• producer surplus (area above supply below price),
• deadweight loss (from distortions like taxes or price ceilings).

Example: Tax incidence intuition

In a competitive market with demand (Q_d=100-2P), supply (Q_s=20+3P), we can compute equilibrium as above ((P^=16, Q^=68)).

If a per-unit tax (t) is imposed, the wedge between consumers’ price and producers’ price creates deadweight loss. Intermediate exams may not require full incidence derivations, but you must be able to:

• state that incidence depends on elasticities,
• explain that both buyers and sellers share the burden,
• show that there is a welfare loss beyond government revenue.

Section 2: Intermediate Microeconomics—Competitive Markets, Game Theory Basics, Market Power, and Welfare

At intermediate level, you move from “markets clear under competition” to “markets may not behave competitively,” while still using demand/supply and equilibrium logic.

Subsection 2.1 Perfect Competition vs Imperfect Competition

Perfect competition assumptions:

• many buyers and sellers,
• homogeneous product,
• perfect information,
• firms are price takers.

A firm chooses output to maximise profit:
[
\pi(q)=pq – C(q)
]
First-order condition:
[
\frac{d\pi}{dq}=p – MC(q)=0 \Rightarrow p=MC
]
Shutdown occurs if the price falls below minimum average variable cost.

Imperfect competition introduces:

• price-setting behaviour,
• market power,
• barriers to entry.

Subsection 2.2 Monopoly and Pricing with Demand

A monopoly faces the market demand curve (Q(P)). It chooses price/output to maximise profit:

[
\pi(P)=P\cdot Q(P)-C(Q(P))
]

A central tool is marginal revenue (MR). For linear demand, MR is linear with twice the slope:

• if demand is (P=a-bQ),
• then MR is (MR=a-2bQ).

Profit maximisation occurs where:
[
MR = MC
]

Then monopoly sets a price above marginal cost, causing deadweight loss relative to competitive equilibrium.

Example: Monopoly with linear demand

Let demand be:
[
P=120-Q
]
Then total revenue (TR=P\cdot Q=(120-Q)Q=120Q-Q^2).
Marginal revenue:
[
MR=\frac{dTR}{dQ}=120-2Q
]
Assume marginal cost is constant at (MC=20).
Set (MR=MC):
[
120-2Q=20 \Rightarrow 2Q=100 \Rightarrow Q_M=50
]
Price:
[
P_M=120-50=70
]
Under competition, where (P=MC), equilibrium would have:
[
P=20 \Rightarrow 20=120-Q \Rightarrow Q_C=100
]

So monopoly restricts output from 100 to 50 and raises price from 20 to 70—creating deadweight loss.

Subsection 2.3 Market Power, Lerner Index, and Elasticity

The Lerner Index links market power to elasticity of demand:

[
\frac{P-MC}{P}=\frac{1}{|\epsilon_d|}
]

So with less elastic demand, the firm can set a larger markup. In exams, you often are asked to:

• compute implied elasticities,
• interpret policy implications (e.g., competition policy).

Subsection 2.4 Oligopoly Basics and Strategic Interaction

Intermediate courses frequently introduce simplified oligopoly/game theory:

• Cournot competition (quantity setting),
• Bertrand competition (price setting),
• possibly introductory dominant strategy reasoning.

Cournot duopoly

Two firms choose quantities (q_1, q_2). Market price depends on total output:
[
P=a-b(q_1+q_2)
]
Profit for firm 1:
[
\pi_1 = P q_1 – C(q_1)
]
First-order conditions yield reaction functions. Nash equilibrium is intersection of reactions.

Bertrand with homogeneous goods

If two firms set prices with identical costs, and goods are homogeneous with no capacity constraints, Bertrand predicts price equals marginal cost (P=MC). Real-world deviations (capacity constraints, differentiation) lead to higher prices.

Subsection 2.5 Externalities and Market Failure

Externalities occur when decision makers fail to bear the full social cost/benefit. Types:

• Negative externalities (pollution): social marginal cost exceeds private marginal cost.
• Positive externalities (education): social marginal benefit exceeds private marginal benefit.

Typical exam structure:

1. Identify private vs social marginal curves.
2. Determine efficient output where marginal social benefit equals marginal social cost.
3. Show the distortions under laissez-faire.
4. Discuss policy tools: taxes (Pigouvian), subsidies, regulation, tradable permits.

Example: Negative externality

Suppose private marginal cost (MC_p = Q), and external marginal cost (MEC = 10). Then social marginal cost:
[
MC_s = MC_p + MEC = Q + 10
]
If demand equals marginal benefit (MB = 50 – Q).
Efficient output solves (MB = MC_s):
[
50 – Q = Q + 10 \Rightarrow 40 = 2Q \Rightarrow Q^*=20
]
Market output ignores MEC: (MB = MC_p):
[
50 – Q = Q \Rightarrow 50=2Q \Rightarrow Q=25
]
So output is too high by 5 units when external costs are ignored.

Subsection 2.6 Taxes, Price Ceilings, and Regulations—Incidence and Efficiency

Even if you can compute equilibrium changes, exams often ask for conceptual understanding:

• tax shifting: elasticities determine who bears the tax,
• efficiency loss: taxation reduces quantities below the efficient level,
• distributional effects: transfers to government and changes in consumer/producer surplus.

Worked numerical intuition (elasticity-based)

If demand is steep/inelastic, consumers are less able to avoid the tax; incidence falls more on consumers. If supply is steep/inelastic, sellers bear more.

A strong answer must:

• state the direction,
• justify using elasticity,
• connect to welfare outcomes (deadweight loss).

Subsection 2.7 Consumer/Producer Surplus and Policy Evaluation

When analysing policies, you should:

• compute or qualitatively evaluate changes in consumer surplus (CS) and producer surplus (PS),
• include government revenue (for taxes) as a transfer (not pure welfare cost),
• identify deadweight loss triangles (efficiency loss).

Be able to explain how:

• price ceilings can cause shortages and rationing,
• minimum prices can cause surpluses,
• per-unit taxes create wedge between buyers and sellers.

Section 3: General Equilibrium, Public Goods, Uncertainty, and Foundations for Macroeconomics

Intermediate economics also includes broader frameworks that connect micro and macro logic: general equilibrium, public goods, and the role of uncertainty and expectations.

Subsection 3.1 General Equilibrium and the Competitive Equilibrium

General equilibrium studies multiple markets simultaneously. The key idea: under perfect competition, equilibrium allocations are efficient in a welfare sense—under certain assumptions.

The Efficiency Link: First and Second Welfare Theorems (core exam content)

• First Welfare Theorem: Any competitive equilibrium yields Pareto efficiency.
• Second Welfare Theorem: Under suitable conditions, any Pareto-efficient allocation can be achieved by a competitive equilibrium with appropriate lump-sum transfers.

Intermediate courses often do not require full proofs, but you must be able to state conditions (complete markets, no externalities, perfect competition, etc.) and interpret what happens when conditions fail.

Subsection 3.2 Pareto Efficiency and Social Welfare

Pareto efficiency means no individual can be made better off without making someone else worse off. In exam scenarios:

• identify whether an allocation is Pareto efficient,
• explain why market failures can violate efficiency.

Simple exchange economy intuition

Two consumers trade two goods. If marginal rates of substitution differ, trade can make both better off, improving efficiency.

Subsection 3.3 Public Goods and the Free-Rider Problem

A public good is:

• non-excludable and non-rival (or approximately so).

Classic example: national defence; in development discussions often: basic public health.

The free-rider problem arises because individuals benefit without paying. In modelling terms:

• private willingness to pay does not aggregate properly (you cannot simply add demand curves vertically in the usual way).

Example: Optimal provision rule

If two consumers derive utility from a public good (G), the efficient provision equates:
[
\sum MB_i(G)=MC(G)
]
where (MB_i) is marginal benefit to consumer (i).

In contrast, if decision makers rely on private marginal benefits only, the provided amount will be too low.

Subsection 3.4 Common Resources and Tragedy of the Commons

Common resources are rival but non-excludable, leading to overuse (e.g., fisheries, grazing land). The private marginal cost of taking resources is below the social marginal cost when congestion or resource depletion exists.

Efficient policy often involves:

• quotas,
• licensing,
• property rights,
• co-management.

Subsection 3.5 Uncertainty and Expected Utility (Intro-Level)

Intermediate micro sometimes introduces uncertainty briefly:

• consumers or firms make choices under risk,
• expected utility theory.

If outcomes (x_1,\ldots,x_n) occur with probabilities (p_1,\ldots,p_n), expected utility is:

[
EU = \sum_{i=1}^{n} p_i u(x_i)
]

Risk-averse individuals have concave (u(\cdot)). Exams often ask:

• interpret risk attitude,
• compute expected utility for simple lotteries.

Subsection 3.6 Transition to Macroeconomics: Consumption, Investment, and Aggregate Demand Links

Macroeconomics aggregates micro foundations. Even when the formal macro model is taught separately, linkages matter for exam writing:

• Consumption depends on income and expectations.
• Investment depends on expected profitability and interest rates.
• Government spending and taxes influence aggregate demand.
• Net exports depend on relative prices and exchange rates.

A strong transition paragraph in exams often correctly connects:

• micro choice → macro consumption function
• firm profit incentives → investment demand
• market power and cost structure → pricing and inflation (especially in imperfect competition contexts)

Section 4: Macroeconomics Core—National Income, Output Determination, Money, Inflation, and Unemployment

Macroeconomics answers the “big questions”: what determines output and employment in the short run, how prices and inflation behave, and how monetary and fiscal policy affect the economy. South African exam papers frequently combine theoretical models with applied interpretation of policy in an open economy with inflation-targeting and exchange rate movements.

Subsection 4.1 Measuring the Economy—GDP, Income, and Expenditure

Two common definitions:

• Expenditure approach:
  [
  Y = C + I + G + (X – M)
  ]
• Income approach (in simplified form) sums factor incomes.

where:

• (Y) is real GDP (or nominal, depending on context),
• (C) consumption,
• (I) investment,
• (G) government spending,
• (X) exports,
• (M) imports.

Nominal vs real GDP

Real GDP adjusts for inflation using a price index:
[
\text{Real GDP} = \frac{\text{Nominal GDP}}{\text{Price level}}
]

In exams, you should be ready to:

• interpret inflation effects,
• explain what deflators/cpi-like indices do.

Subsection 4.2 The Keynesian Cross—Short-Run Output Determination

A common short-run model assumes prices are sticky, so output adjusts to bring aggregate demand in line with actual output.

Aggregate demand can be modelled as:
[
AD = C(Y-T) + I + G
]
where:

• (T) is taxes,
• consumption depends on disposable income (Y-T).

In the Keynesian cross, equilibrium output satisfies:
[
Y = AD
]

Example: Simple consumption function

Let:
[
C = a + b(Y-T)
]
Suppose (a=50), (b=0.8), (T=100), (I=100), (G=150).
Then:
[
AD = 50 + 0.8(Y-100) + 100 + 150
]
[
AD = 50 + 0.8Y – 80 + 350
]
[
AD = 0.8Y + 320
]
Set (Y=AD):
[
Y = 0.8Y + 320 \Rightarrow 0.2Y = 320 \Rightarrow Y = 1,600
]

Multiplier intuition: if government spending increases, equilibrium output rises by more than the initial increase, by the multiplier (\frac{1}{1-b}).

Subsection 4.3 The Fiscal Multiplier and Government Policy

If taxes are proportional or changes are lump-sum, multipliers differ. For constant marginal propensity to consume (b):

• government spending multiplier: ( \frac{1}{1-b} )
• tax multiplier: ( -\frac{b}{1-b} ) for lump-sum tax changes in simplified models.

Numerical illustration

Using (b=0.8), government multiplier:
[
\frac{1}{1-0.8} = \frac{1}{0.2}=5
]
So if (G) rises by 20, output rises by 100 in this model.

Subsection 4.4 Money, Interest Rates, and the LM Intuition

Intermediate macro often uses money-market logic:

• Money demand increases with income and decreases with interest rates.
• The nominal interest rate equilibrates money supply and money demand.

A simplified money demand function:
[
\frac{M}{P} = L(Y,i)
]
In a basic liquidity preference model:

• as (Y) increases, people hold more money,
• as (i) increases, opportunity cost of holding money rises, so money demand falls.

Subsection 4.5 Aggregate Demand with Interest Rates: IS-LM Simplification (Conceptual)

Even if full IS-LM diagrams aren’t required, you must understand:

• IS curve: combinations of output and interest rates where goods market equilibrium holds.
• LM curve: combinations where money market equilibrium holds.

Policy:

• monetary expansion shifts LM and can lower interest rates, raising investment and output.
• fiscal expansion shifts IS, raising interest rates and potentially crowding out investment.

Subsection 4.6 Inflation—Demand-Pull vs Cost-Push and the Phillips Curve Logic

Inflation mechanisms taught in intermediate courses often include:

• demand-driven inflation (aggregate demand increases),
• cost-push inflation (input costs rise, wages rise),
• expectations and the Phillips curve.

A basic augmented Phillips curve:
[
\pi = \pi^e – \alpha(u-u^*) + \text{shocks}
]
where:

• (\pi) is inflation,
• (\pi^e) expected inflation,
• (u) unemployment,
• (u^*) natural rate.

Key exam point: persistent trade-offs fade as expectations adjust; in the long run, inflation affects nominal variables while unemployment returns to natural levels.

Subsection 4.7 Unemployment—Types and Macroeconomic Interpretation

Unemployment is not only “too little demand.” You should differentiate:

• frictional (search costs),
• structural (mismatch of skills, geography, technology),
• cyclical (macroeconomic downturn).

In South African discussions, structural unemployment and labour market rigidities often appear in exam questions. Strong answers tie:

• demand management (Keynesian) to cyclical unemployment,
• education/skills and labour market policy to structural unemployment.

Subsection 4.8 Open-Economy Macro: Exchange Rates, Net Exports, and the Trade Balance

For South Africa, open-economy components matter. Net exports:
[
NX = X – M
]

Exchange rates influence net exports through relative price effects:

• depreciation can increase exports and reduce imports if conditions (elasticities, pass-through) hold.

However, in the short run, depreciation can worsen trade balance due to contracts and timing (J-curve effects). Exams sometimes require qualitative justification rather than full modelling.

Section 5: Integrated Application—Policy Evaluation in South Africa Context, Stabilisation, and Exam Problem-Solving Framework

This final section turns theory into exam-ready problem solving. It also places macro policy into a South African policy environment—without relying on memorised “current events” that may change between exam sittings. Instead, it emphasises the policy logic likely to be tested: how fiscal and monetary policy interact with inflation, unemployment, and output in an open economy.

Subsection 5.1 Fiscal vs Monetary Policy—Objectives and Trade-offs

Fiscal policy (changes in (G), taxes (T)) aims at:

• stabilising output and employment,
• supporting long-run development (infrastructure, human capital),
• redistributive aims (social grants, progressive taxation—if included in course discussion).

Monetary policy (central bank actions affecting money supply and interest rates) aims at:

• controlling inflation,
• supporting financial stability,
• influencing exchange rates and demand via interest rates.

In an exam, if asked to evaluate a policy, structure your answer as:

1. Identify channel: IS (demand), LM (money/interest), exchange rate (net exports).
2. Identify expected short-run effect: output, unemployment, inflation.
3. Identify possible medium/long-run adjustment: expectations, wage bargaining, debt dynamics.
4. Consider open-economy risks: imported inflation, exchange rate pass-through.

Subsection 5.2 Using the Keynesian Cross for Policy Questions (Step-by-Step Method)

When a question gives:

• consumption function (C = a + b(Y-T)),
• investment (I) (sometimes fixed),
• government (G),
• taxes (T),

you should compute equilibrium output by:

1. Write (AD = C + I + G).
2. Express consumption in terms of (Y): substitute (T).
3. Set (Y = AD).
4. Solve for (Y).
5. Compare scenarios (before vs after the policy change).
6. Compute change in output and interpret using multiplier.

Example: Tax cut and output effect

Using earlier parameters (a=50), (b=0.8), (I=100), (G=150), with (T=100).
We found (Y=1,600).

Now suppose taxes fall by 20: (T'=80).
Recompute:
[
AD = 50 + 0.8(Y-80) + 100 + 150
]
[
AD = 50 + 0.8Y – 64 + 350
]
[
AD = 0.8Y + 336
]
Equilibrium:
[
Y=0.8Y+336 \Rightarrow 0.2Y=336 \Rightarrow Y'=1,680
]
Change in output:
[
\Delta Y = 1,680 – 1,600 = 80
]

Tax multiplier implied:
[
\Delta Y / \Delta T = 80 / (-20) = -4
]
So a negative tax change increases output.

How to interpret: consumers increase disposable income; consumption rises; equilibrium output expands.

Subsection 5.3 Inflation and Policy—How to Link Demand Shocks to Price Changes

In intermediate macro, even when the Keynesian cross is used for output, exam questions often ask:

• why inflation might rise when output is above potential,
• how policy may be contractionary if inflation is too high.

A common approach:

• If output is above potential, demand pressure raises inflation.
• Central bank raises interest rates to reduce demand, lowering output growth and inflation.

In an open economy:

• higher domestic interest rates can attract capital, supporting the currency (or affect it depending on risk).
• appreciation lowers import prices, reducing inflation (subject to pass-through).

Subsection 5.4 South Africa: Policy Interpretation through the Lens of Structural Constraints

South African macro problems frequently include:

• unemployment and skills mismatch,
• low investment and productivity constraints,
• energy and logistics constraints,
• public debt and fiscal space issues,
• exchange-rate sensitivity and imported inflation risk.

In exams, you do well when you explicitly state which macro model assumptions are unrealistic and then correct:

• If labour markets are structurally rigid, demand stimulus may not eliminate unemployment proportionally.
• If inflation is driven by supply shocks (oil, food, exchange rate), demand management alone may not be sufficient.
• If government borrowing costs are high, fiscal expansions may face crowding-out or debt sustainability concerns.

Subsection 5.5 Common Exam Question Patterns and How to Answer

Below are recurring patterns and a high-scoring response template.

Pattern A: “Show how equilibrium output changes when (G) increases by …”

Template:

1. State equilibrium condition (Y=AD).
2. Substitute new (G) into (AD).
3. Solve for (Y) before and after.
4. Compute (\Delta Y).
5. Conclude using the multiplier ( \frac{1}{1-b} ) (if applicable).

Pattern B: “Explain policy impact on inflation and unemployment”

Template:

1. Link policy to output gap (demand pressure).
2. Use Phillips curve logic: higher inflation expectations adjust; long-run unemployment returns to natural rate.
3. Mention supply shocks/expectations as key modifiers.

Pattern C: “Evaluate external shock (exchange rate depreciation)”

Template:

1. Depreciation affects import prices → cost-push inflation.
2. It also changes net exports (assuming elasticities) → demand for domestic output rises.
3. Net effect on output depends on whether inflation reduces real purchasing power strongly enough to offset export gains.
4. Central bank may tighten policy; higher rates affect output negatively but may stabilise inflation.

Subsection 5.6 Integrating Micro and Macro: Demand, Labour Markets, and Business Pricing

A sophisticated exam answer connects micro behaviour to macro outcomes:

• In imperfect competition, firms may have pricing power, making inflation more persistent when costs rise.
• Labour markets: wage-setting can cause sticky wages; if wages adjust slowly, unemployment responds differently than in the textbook flexible-wage model.
• Tax incidence: if a tax raises business costs, it can shift supply and raise prices—affecting CPI inflation and real output.

You should avoid claiming that one single factor explains everything. Instead:

• Use the model to show a main channel,
• then mention additional channels that may dominate under certain conditions.

Subsection 5.7 A Worked Multi-Step Integrated Scenario (Micro + Macro)

Consider a simplified story consistent with intermediate course logic:

• A government introduces an excise tax on fuel, increasing transport costs for firms.
• Firms’ marginal costs rise (micro), shifting supply left (micro-to-market).
• At the macro level, aggregate supply becomes weaker; inflationary pressures rise.
• The central bank responds by raising interest rates to dampen demand and inflation.

To answer:

1. Micro: increased input costs raise (MC), lowering output at any given price (or raising price at any given quantity).
2. Market diagram logic: supply shifts left/up, raising equilibrium price.
3. Macro: higher prices reduce real incomes, potentially reducing consumption (C).
4. Policy response: tighter monetary policy reduces equilibrium output via interest rate effect on investment.
5. Outcome: output growth slows; inflation eventually falls if expectations stabilise.

A high-grade answer explicitly names:

• the inflation channel (cost-push via higher marginal costs),
• the output channel (demand contraction via higher interest rates),
• the expectations channel (augmented Phillips curve: inflation depends on expected inflation).

Subsection 5.8 Study Strategy for ECN2AB2-Type Exams

To turn these notes into marks, use a disciplined approach:

1. Diagram mastery (non-negotiable):

   • Budget line and indifference curves,
   • Demand/supply and welfare triangles,
   • Monopoly MR and marginal cost intersection,
   • Phillips curve and unemployment trade-off explanation,
   • Open-economy exchange rate logic (qualitative).

2. Calculation drills:

   • Equilibrium price/quantity from linear functions,
   • Elasticity computation from given formulas or changes,
   • Keynesian equilibrium output with consumption functions,
   • Multiplier logic with (b) given.

3. Policy writing drills:

   • For every policy question, explicitly state:
     • channel → sign of effect → magnitude (if possible) → limitations
   • Limitations should reflect structural constraints, open economy, and expectations.

4. Exam answer structure (fast template):

   • Start with the model/equation,
   • do the computation,
   • interpret results in words,
   • mention assumptions and limitations.

Quick Reference Tables (For Revision)

Table 1: Key Conditions and Relationships

Topic	Core Condition / Relationship	What You Should State in an Exam
Consumer optimum	Tangency: (MU_x/MU_y = p_x/p_y)	Demand depends on relative prices and income
Cobb–Douglas demand	With (U=x^{0.5}y^{0.5}): (x=\frac{m}{2p_x}), (y=\frac{m}{2p_y})	Income split across goods
Competitive firm	(p=MC) (produce where price equals marginal cost)	Supply derived from marginal cost
Monopoly	(MR=MC)	Monopoly restricts output and raises price
Welfare under competition	Competitive equilibrium is Pareto efficient (under assumptions)	Efficiency relies on no externalities, perfect competition, etc.
Public goods efficiency	(\sum MB_i(G)=MC(G))	Add marginal benefits vertically
Keynesian equilibrium	(Y=AD)	Output adjusts until demand equals production
Multiplier	( \text{Gov. spending multiplier}=\frac{1}{1-b} )	Output changes more than initial policy due to induced consumption
Tax multiplier (lump sum simplified)	( -\frac{b}{1-b} )	Output falls when taxes rise (sign and magnitude)

Table 2: Example Outputs (Consistency Check)

Scenario	Parameters	Result
Baseline Keynesian cross	(a=50), (b=0.8), (T=100), (I=100), (G=150)	(Y=1,600)
After tax cut	Same, but (T=80)	(Y=1,680)
After output changes	(\Delta T=-20)	(\Delta Y=+80)

Final Consolidated Exam Mindset

Intermediate microeconomics and macroeconomics require two complementary strengths: analytical precision (equations, equilibrium solving, welfare calculations) and clear economic interpretation (what changes when, and why). In South African university and TVET contexts, marks often come from demonstrating that you can: (1) translate model assumptions into correct diagrams, (2) compute the required equilibrium or policy effect accurately, and (3) write an interpretation that shows you understand economic mechanisms rather than only procedures.

Keep your work organised, label diagrams clearly, show substitution steps in algebra, and always link your final numbers back to economic meaning—especially for policy and welfare questions where explanation can be as important as calculation.