Semester 2 2025 - DUE September 2025; 100%
TRUSTED Complete, trusted solutions and
explanations.
MULTIPLE CHOICE,ASSURED EXCELLENCE
Complete answers — open economy macro, exchange rates,
and policy
1. Expansionary fiscal policy in an open economy with fixed
exchange rates, initially at natural output (18 marks)
Setup / intuition (short): With a fixed exchange rate and an
open economy, fiscal expansion (↑G or ↓T) shifts IS right.
Under a fixed peg, the central bank must intervene in forex
markets to keep the exchange rate fixed. These interventions
alter the domestic money supply so monetary conditions end
up accommodating the fiscal expansion — making fiscal policy
very effective.
Step-by-step mechanism
1. Start at equilibrium: IS₀, LM₀, FE (foreign exchange
equilibrium), output = Y_n.
2. Fiscal expansion → IS₀ → IS₁ (right). At original money
supply, this raises interest rates.
, 3. Higher domestic interest rate attracts capital inflows →
pressure for currency appreciation.
4. To maintain the peg the central bank buys foreign
currency / sells domestic currency, increasing the
domestic money supply.
5. Money supply ↑ → LM shifts right (LM₀ → LM₁). This
lowers interest rates back and increases output further.
6. Final equilibrium: higher Y, interest rate close to original,
fixed exchange rate maintained. Monetary policy has been
forced to accommodate fiscal expansion.
Diagram (Mundell–Fleming IS-LM-FE) — hand-draw
Vertical axis: interest rate (i). Horizontal: output (Y).
Draw IS curve (downward sloping in (i,Y) space), LM curve
(upward sloping in (Y,i) orientation), and FE near horizontal
(for perfect capital mobility FE is horizontal at world i*;
with imperfect mobility draw steep).
Show IS shifting right to IS₁, then LM shifting right due to
central bank interventions. Show final higher Y at same
exchange rate.
Exam note / conclusion: Under fixed exchange rates, fiscal
policy is potent because sterilisation is costly: the central bank
must adjust money supply to defend the peg, effectively giving
a monetary expansion that reinforces fiscal stimulus.
, 2. Dollarization vs. Optimum Currency Area (OCA) (10 marks)
Dollarization
Definition: A country adopts a foreign currency (often the
US dollar) either officially (full dollarization) or unofficially
(de facto).
Features: No independent monetary policy, no seigniorage
(or greatly reduced), limited lender-of-last-resort capacity.
Implemented unilaterally.
Benefits: Credibility (inflation control), lower transaction
costs, exchange-rate certainty.
Costs: Loss of monetary independence, inability to respond
to local shocks with monetary policy, loss of seigniorage.
Optimum Currency Area (OCA)
Definition: A region where it is economically efficient to
share a single currency or have tightly fixed exchange rates
because benefits (reduced transaction costs, price
transparency) outweigh costs (loss of independent
monetary policy).
Classic OCA criteria (Mundell, McKinnon, Kenen): labor
mobility, capital mobility, similar business cycles, fiscal
transfer mechanisms, price and wage flexibility, openness
and trade integration.