Semester 2 2025 - DUE September 2025; 100%
TRUSTED Complete, trusted solutions and
explanations.
1 — Expansionary fiscal policy under a fixed exchange rate
(open economy) (18)
Setup / assumptions
Open economy, fixed exchange rate (peg).
Economy initially at natural (potential) output Y*
(internal balance).
Perfect or high capital mobility (standard Mundell–
Fleming setup).
Mechanics (Mundell–Fleming intuition)
1. Government increases G (or cuts taxes) → aggregate
demand (AD) increases → IS curve (or goods-market)
shifts right: IS → IS′.
2. Higher demand raises output and puts upward pressure
on the domestic interest rate (i > i_world).
3. With fixed exchange rates and capital mobility, the higher
domestic interest rate attracts capital inflows.
, 4. To maintain the peg, the central bank buys foreign
currency and sells domestic currency → this increases the
domestic money supply.
5. Increased money supply shifts LM right (LM → LM′) until
the interest rate returns to the world rate. The net result
is higher output (Y > Y*) without a change in the
exchange rate.
Net effect
Output rises above Y* (expansion works).
No change in exchange rate (by assumption central bank
defends peg).
Money supply increases (due to reserve accumulation).
The fiscal expansion is therefore more potent with fixed
rates than under flexible rates (because monetary
expansion is induced endogenously).
Graph you should draw (IS–LM–BP / Mundell–Fleming)
Horizontal axis: Y (output). Vertical axis: i (interest rate).
Draw IS, LM, and BP where BP is horizontal at i_world (if
perfect capital mobility).
Show IS shifting right to IS′.
Show LM shifting right (from central bank foreign reserve
purchases) until i returns to i_world.
, Mark initial equilibrium (E), intermediate (higher i), final
equilibrium (E′) with higher Y and same i.
Exam bullet points
Explain capital mobility assumption.
Show central bank interventions and reserve
accumulation.
Mention possibility of overheating if expansion too large
→ inflationary pressures later.
If capital mobility is low, fiscal effectiveness is weaker (BP
not horizontal).
2 — Dollarization vs Optimum Currency Area (OCA) (10)
Dollarization
Definition: A country abandons its own currency and
adopts another country’s currency (e.g., US dollar) either
officially or unofficially.
Benefits: eliminates currency risk & exchange cost; price
stability if adopting a stable currency; lower nominal
interest rates; encourages trade/investment with
currency issuer.
Costs: loss of independent monetary policy and lender-of-
last-resort; cannot respond to asymmetric shocks via