2025 HKDSE Economics Practice Paper with Answers

Statement (1) is correct: Country X can produce more solar panels ($40 > 30$) and more wind turbines ($20 > 10$) than Country Y using the same 1 unit of resources, so Country X has an absolute advantage in both goods.
Statement (2) is correct: The opportunity cost of producing $1\text{ unit of solar panels}$ in Country X is $\frac{20}{40} = 0.5\text{ wind turbines}$, whereas in Country Y it is $\frac{10}{30} \approx 0.33\text{ wind turbines}$. Country Y has a lower opportunity cost in solar panels, so it has a comparative advantage in solar panels.
Statement (3) is correct: For Country X, the cost of $1\text{ unit of wind turbines}$ is $2\text{ units of solar panels}$. For Country Y, the cost of $1\text{ unit of wind turbines}$ is $3\text{ units of solar panels}$. The mutually beneficial terms of trade for 1 unit of wind turbines lie strictly between $2\text{ units of solar panels}$ and $3\text{ units of solar panels}$. Since $2.5$ falls within this range, both countries will gain from trade.
Therefore, (1), (2) and (3) are all correct.

Award 1 mark for the correct answer D. Award 0 marks for incorrect options A, B, or C.

Initial situation:
Required reserves $= 20\% \times $8\,000\text{ million} = $1\,600\text{ million}$.
Actual reserves $= $2\,000\text{ million}$.
Initial excess reserves $= $2\,000 - $1\,600 = $400\text{ million}$.

When the public withdraws $$400\text{ million}\$ cash, bank reserves decrease by $$400\text{ million}$, so new total reserves $= $2\,000 - $400 = $1\,600\text{ million}$.

With required reserve ratio $r = 0.20$ and zero excess reserves held by banks in the final state, the maximum total deposits supported by $$1\,600\text{ million}\$ of reserves is:
$$\text{Max deposits} = \frac{\$1\,600\text{ million}}{0.20} = \$8\,000\text{ million}.$$

However, the withdrawal itself directly reduces deposits initially by $$400\text{ million}$, bringing remaining deposits to $$7\,600\text{ million}\$. But if the question asks for the maximum contraction in total deposits when banks had initial excess reserves:
Initial deposits \$= \$8\,000\text{ million}\$.
If reserves become $$1\,600\text{ million}$, max possible deposits $= \frac{$1\,600}{0.2} = $8\,000\text{ million}$, meaning if banks fully expand loans, total deposits could remain $$8\,000\text{ million}\$, so deposit contraction could be $$0$.
Wait, if banks do not hold excess reserves (meaning the initial $$400\text{ million}\$ was excess reserves), the maximum contraction occurs if all $$400\text{ million}$ loss of reserves leads to multiple contraction:
Change in deposits $= \Delta R \times \frac{1}{r} = -$400\text{ million} \times \frac{1}{0.20} = -$2\,000\text{ million}$.
Thus, the maximum contraction in deposits is $$2\,000\text{ million}$.

Award 1 mark for C. Award 0 marks for any other option.

Price discrimination is the practice of charging different prices for the same good/service where price differences are not due to cost differences.
The necessary conditions for price discrimination are:
1. The seller must possess market power (option B).
2. The seller must be able to segment the market and prevent arbitrage/resale (option C).
3. The distinct sub-markets must have different price elasticities of demand (option D).
Different marginal costs across groups are NOT required for price discrimination (in fact, if price differences merely reflected cost differences, it would not be price discrimination). Therefore, option A is NOT essential.

Award 1 mark for A. Award 0 marks for B, C, or D.

Calculate the Marginal Cost (MC) for each unit of output:
- 1st unit: $\text{MC} = $10 - $0 = $10$
- 2nd unit: $\text{MC} = $22 - $10 = $12$
- 3rd unit: $\text{MC} = $36 - $22 = $14$
- 4th unit: $\text{MC} = $52 - $36 = $16$
- 5th unit: $\text{MC} = $70 - $52 = $18$
- 6th unit: $\text{MC} = $92 - $70 = $22$

For a price-taking firm, the profit-maximizing condition is $\text{MR} = P = \text{MC}$ (with $\text{MC}$ rising).
Given $P = $16$, $\text{MR} = \text{MC} = $16$ at an output of $4\text{ units}$.

At output $= 4\text{ units}$:
$$\text{Total Revenue (TR)} = P \times Q = \$16 \times 4 = \$64$$
$$\text{Total Cost (TC)} = \text{TFC} + \text{TVC} = \$30 + \$52 = \$82$$
$$\text{Profit} = \text{TR} - \text{TC} = \$64 - \$82 = -\$18$$
Since $P = $16 > \text{AVC} = \frac{$52}{4} = $13$, the firm covers its variable costs and should continue production in the short run.
Thus, the profit-maximizing output is $4\text{ units}$ and the profit is $-$18$ (loss of $$18$). Option B is correct.

Award 1 mark for B. Award 0 marks for A, C, or D.

An effective import quota raises the domestic price of olive oil above the world price $P_w$.
1. Because the domestic price rises, domestic quantity supplied increases, so domestic producer surplus increases (ruling out A and C).
2. Domestic quantity demanded decreases, so the total quantity consumed decreases (ruling out D).
3. The decrease in consumer surplus is given by areas $a + b + c + d$, where $a$ is the transfer to domestic producers (increase in producer surplus), $c$ is the quota rent captured entirely by the government via license auction, and $b$ and $d$ are deadweight losses (production and consumption distortions).
Thus, the decrease in consumer surplus exceeds the sum of the gain in producer surplus ($a$) and government revenue ($c$) by the deadweight loss ($b + d$). Statement B is correct.

Award 1 mark for B. Award 0 marks for incorrect options A, C, or D.

Definitions of money supply in Hong Kong:
- M1 = Public currency + Demand deposits with licensed banks.
- M2 = M1 + Savings deposits with licensed banks + Time deposits with licensed banks + NCDs issued by licensed banks held by the public.
- M3 = M2 + Deposits with restricted licence banks and deposit-taking companies + NCDs issued by restricted licence banks and deposit-taking companies held by the public.

Transactions:
1. Demand deposits with licensed banks decrease by $$50\,000\$, so M1 decreases by $$50\,000$.
2. The funds are moved into NCDs issued by restricted licence banks ($$30\,000\$) and deposits with deposit-taking companies ($$20\,000$). Neither of these items belongs to M1 or M2; both belong to M3 (specifically the components added to M2 to form M3).
3. Therefore, M2 decreases by $$50\,000\$ (since M1 dropped by $$50\,000$ and no M2 component increased).
4. In M3, the reduction of $$50\,000\$ in M2 is exactly offset by an increase of $$30\,000 + $20\,000 = $50\,000$ in non-M2 M3 components. Hence, M3 remains unchanged.
Therefore, M1 decreases, M2 decreases, and M3 remains unchanged. Option A is correct.

Award 1 mark for A. Award 0 marks for B, C, or D.

The relationship between marginal revenue and price elasticity of demand ($E_d$) is given by:
$$\text{MR} = P\left(1 - \frac{1}{E_d}\right)$$
When marginal revenue is positive ($\text{MR} > 0$):
$$P\left(1 - \frac{1}{E_d}\right) > 0 \implies 1 - \frac{1}{E_d} > 0 \implies E_d > 1$$
This means the firm is operating in the elastic region of its demand curve.
- A is not necessarily true because profit maximization requires $\text{MR} = \text{MC}$, not just $\text{MR} > 0$.
- C is incorrect because a monopoly typically does not produce where ATC is minimized.
- D is incorrect because a single-price monopoly inherently creates a deadweight loss when $P > \text{MC}$.
Thus, statement B is definitely correct.

Award 1 mark for B. Award 0 marks for A, C, or D.

Calculate the Marginal Product (MP) of each unit of labour:
- 1st unit of labour: $\text{MP}_1 = 25 - 0 = 25\text{ loaves}$
- 2nd unit of labour: $\text{MP}_2 = 60 - 25 = 35\text{ loaves}$
- 3rd unit of labour: $\text{MP}_3 = 100 - 60 = 40\text{ loaves}$
- 4th unit of labour: $\text{MP}_4 = 130 - 100 = 30\text{ loaves}$
- 5th unit of labour: $\text{MP}_5 = 150 - 130 = 20\text{ loaves}$
- 6th unit of labour: $\text{MP}_6 = 160 - 150 = 10\text{ loaves}$

The marginal product increases up to the 3rd unit of labour ($25 \to 35 \to 40$) and begins to decrease when employing the 4th unit of labour ($40 \to 30$). Therefore, the law of diminishing marginal returns sets in with the employment of the 4th unit of labour. Option C is correct.

Award 1 mark for C. Award 0 marks for incorrect options A, B, or D.

Calculation of opportunity costs:
- Country A requires fewer hours of labour to produce both goods (4 hours < 6 hours for smartphones; 2 hours < 5 hours for garments). Thus, Country A has an absolute advantage in producing both goods. Statement (1) is correct.

Opportunity cost of producing 1 unit of smartphone:
- In Country A: \(4 / 2 = 2\) units of garments.
- In Country B: \(6 / 5 = 1.2\) units of garments.
Country B has a lower opportunity cost in producing smartphones, so Country B has a comparative advantage in smartphones, while Country A has a comparative advantage in garments. Statement (2) is incorrect.

Mutual gains from trade:
- The mutually beneficial terms of trade for 1 unit of smartphone is between \(1.2\) units of garments and \(2\) units of garments.
- At \(1\text{ smartphone} = 1.5\text{ garments}\), Country A (which exports garments and imports smartphones) only needs to give up \(1.5\) garments to obtain \(1\) smartphone, which is less than its domestic opportunity cost of \(2\) garments. Thus, Country A gains from trade. Statement (3) is correct.

Therefore, (1) and (3) only are correct.

[1 mark] B: (1) and (3) only.
[0 marks] Any other option.

When an effective import quota is imposed on an imported good:
1. The domestic supply shifts to the right by the quota amount, resulting in a domestic equilibrium price that is higher than the world price \(P_w\).
2. At a higher domestic price, domestic producers expand their output along the domestic supply curve. Consequently, the producer surplus of domestic wheat growers definitely increases (Option B is correct).
3. Total expenditure by domestic consumers depends on the price elasticity of demand for wheat, so it does not definitely increase (Option A is incorrect).
4. An import quota generates quota rents for quota holders rather than tariff revenue for the government unless the quota licences are auctioned (Option C is incorrect).
5. As the domestic price increases, the domestic quantity demanded of wheat falls (Option D is incorrect).

[1 mark] B: The producer surplus of domestic wheat growers increases.
[0 marks] Any other option.

Under the definitions of money supply in Hong Kong:
- M1 = Legal tender notes and coins held by the public + demand deposits with licensed banks.
- M2 = M1 + savings deposits with licensed banks + time deposits with licensed banks + negotiable certificates of deposit (NCDs) issued by licensed banks held by the public.
- M3 = M2 + customer deposits with restricted licence banks and deposit-taking companies (DTCs) + NCDs issued by restricted licence banks and DTCs held by the public.

Effects on M1:
- Savings deposits are not included in M1.
- Cash held by the public increases by HK$60,000.
- Therefore, M1 increases by HK$60,000.

Effects on M3:
- Savings deposits in a licensed bank decrease by HK$100,000.
- Cash held by the public increases by HK$60,000 (which is part of M1, and thus part of M3).
- NCDs issued by a deposit-taking company held by the public increase by HK$40,000 (which is included in M3).
- Net change in M3 = \(-\text{HK}\$100,000 + \text{HK}\$60,000 + \text{HK}\$40,000 = 0\).
- Therefore, M3 remains unchanged.

Thus, Option A is correct.

[1 mark] A: M1 increases by HK$60,000 and M3 remains unchanged.
[0 marks] Any other option.

1. Initially:
- Required reserve ratio \(r = 25\% = 0.25\).
- Initial deposits \(D_0 = \$2\,000\text{ million}\).
- Initial reserves \(R_0 = \$500\text{ million} = 0.25 \times \$2\,000\text{ million}\) (no excess reserves).
- Initial money supply \(M_0 = C_0 + D_0 = C_0 + 2\,000\).

2. After the cash withdrawal of $100 million:
- Cash held by the public increases by \(\Delta C = +\$100\text{ million}\).
- Bank reserves decrease to \(R_1 = \$500 - \$100 = \$400\text{ million}\).
- Maximum possible deposits become \(D_1 = R_1 / r = 400 / 0.25 = \$1\,600\text{ million}\).
- Change in deposits \(\Delta D = \$1\,600 - \$2\,000 = -\$400\text{ million}\).

3. Overall change in money supply:
- \(\Delta M = \Delta C + \Delta D = +\$100\text{ million} + (-\$400\text{ million}) = -\$300\text{ million}\).

Therefore, the maximum possible money supply decreases by $300 million (Option B).

[1 mark] B: decrease by $300 million.
[0 marks] Any other option.

Third-degree price discrimination involves charging different prices to different identifiable consumer groups based on their differing price elasticities of demand for an identical good/service, where resale between groups is prevented.

- Option A: Charging different prices to students and adults for identical cinema tickets upon verifying student IDs is third-degree price discrimination.
- Option B: Quantity discounting (20% off on second item) is second-degree price discrimination.
- Option C: Selling basic vs premium software versions reflects product differentiation (different goods/costs), not price discrimination of the same product.
- Option D: Block pricing based on consumption volume is second-degree price discrimination.

[1 mark] A: A cinema charging students a lower ticket price than adults for the same movie screening after verifying student IDs.
[0 marks] Any other option.

When a price ceiling is set at \(P = MC\):
1. The monopolist becomes a price taker at \(P = MC\). The marginal revenue curve is a horizontal line at \(MR = MC\). The firm maximizes profit where \(P = MC\), which produces the allocatively efficient level of output. Thus, deadweight loss is completely eliminated. Statement (1) is correct.
2. In an unconstrained monopoly, the firm produces where \(MR = MC < P\), which is strictly less than the competitive output where \(P = MC\). Hence, under the price ceiling \(P = MC\), output increases. Statement (2) is correct.
3. Total revenue is \(TR = P \times Q = MC \times Q = TVC\). Since \(\text{Profit} = TR - TVC - TFC = -TFC\), if the firm has positive fixed costs (\(TFC > 0\)), it will make an economic loss equal to \(TFC\), rather than zero economic profit. Statement (3) is incorrect.

Therefore, (1) and (2) only are correct.

[1 mark] B: (1) and (2) only.
[0 marks] Any other option.

We compute the Marginal Product (\(MP\)) of labour for each additional unit of labour:
- 1st unit of labour: \(MP_1 = 12 - 0 = 12\)
- 2nd unit of labour: \(MP_2 = 28 - 12 = 16\)
- 3rd unit of labour: \(MP_3 = 42 - 28 = 14\)
- 4th unit of labour: \(MP_4 = 52 - 42 = 10\)
- 5th unit of labour: \(MP_5 = 58 - 52 = 6\)

The marginal product increases from 12 to 16 when employing the 2nd worker, and then begins to decrease from 16 to 14 upon employing the 3rd worker.
Thus, the law of diminishing marginal returns sets in when the 3rd unit of labour is employed.

[1 mark] B: 3rd.
[0 marks] Any other option.

From the table:
- Total Fixed Cost (\(TFC\)) is the total cost at 0 output: \(TFC = \$60\).
- Total Variable Cost (\(TVC\)) at output \(Q\) is \(TC(Q) - TFC\).

Let's evaluate each option:
- Option A: At \(Q = 4\), Average Fixed Cost \(AFC = TFC / Q = 60 / 4 = \$15\). This is correct.
- Option B: Marginal cost of the 3rd unit is \(MC(3) = TC(3) - TC(2) = 150 - 120 = \$30\) (not $20).
- Option C: Total variable cost at \(Q = 2\) is \(TVC(2) = TC(2) - TFC = 120 - 60 = \$60\) (not $120).
- Option D: At \(Q = 5\), \(TVC(5) = 245 - 60 = 185\). Thus \(AVC(5) = 185 / 5 = \$37\) (not $49).

[1 mark] A: The average fixed cost of producing 4 units of output is $15.
[0 marks] Any other option.

Opportunity cost is the highest value of the alternatives forgone. If Chloe chooses to attend the festival, she gives up the opportunity to work the freelance assignment ($900) AND sell the festival ticket to her classmate ($650). Since she can perform the assignment and sell the ticket at the same time if she does not attend, the total value forgone is \(\$900 + \$650 = \$1,550\). The initial purchase price of $500 is a sunk cost and does not affect the opportunity cost.

Award [1 mark] for selecting option D. Award [0 marks] for any other response.

Average variable cost (\(\text{AVC}\)) is calculated as \(\text{Total Variable Cost (TVC)} / \text{Total Output (Q)}\), which equals \((\text{Labour} \times \$100) / Q\) or \(\text{Wage} / \text{Average Product (AP)}\).
- For \(L = 1\): \(\text{AVC} = \$100 / 15 = \$6.67\)
- For \(L = 2\): \(\text{AVC} = \$200 / 36 = \$5.56\)
- For \(L = 3\): \(\text{AVC} = \$300 / 60 = \$5.00\)
- For \(L = 4\): \(\text{AVC} = \$400 / 78 = \$5.13\)
- For \(L = 5\): \(\text{AVC} = \$500 / 85 = \$5.88\)
Thus, average variable cost reaches its minimum at \(L = 3\).

Award [1 mark] for selecting option B. Award [0 marks] for any other response.

(1) With the same resources, Country A produces 40 smartphones while Country B produces 30. Country A has an absolute advantage in smartphones. Thus (1) is correct.
(2) In Country A, the opportunity cost of 1 tablet is \(40 / 80 = 0.5\) smartphone. In Country B, the opportunity cost of 1 tablet is \(30 / 90 = 0.33\) smartphone. Since \(0.33 < 0.5\), Country B has a lower opportunity cost and therefore a comparative advantage in producing tablets. Thus (2) is correct.
(3) Country A's cost of 1 smartphone is 2 tablets, and Country B's cost is 3 tablets. A mutually beneficial exchange rate lies between 2 and 3 tablets per smartphone. At 1 smartphone = 2.5 tablets, Country A will specialize in and export smartphones. Thus (3) is correct.

Award [1 mark] for selecting option D. Award [0 marks] for any other response.

- \(\text{M1} = \text{Legal tender held by public} + \text{Demand deposits with licensed banks}\). Cash held by public increases by HK$10 000, so M1 increases by HK$10 000.
- \(\text{M2} = \text{M1} + \text{Savings and time deposits with licensed banks} + \text{NCDs issued by licensed banks}\). Time deposits drop by HK$80 000, cash rises by HK$10 000, savings deposits rise by HK$40 000, while NCDs issued by restricted licence banks are not in M2. So M2 decreases by HK$30 000.
- \(\text{M3} = \text{M2} + \text{Deposits with restricted licence banks and deposit-taking companies} + \text{NCDs issued by restricted licence banks and deposit-taking companies}\). M3 changes by \(-\$80\,000 + \$10\,000 + \$40\,000 + \$30\,000 = 0\), so M3 remains unchanged.
Hence, M1 increases while M3 remains unchanged.

Award [1 mark] for selecting option A. Award [0 marks] for any other response.

Price discrimination refers to charging different prices for the same good or service where the price differences are not caused by differences in production or service costs. A software firm charging students a lower subscription price than corporate users for the exact same cloud software package is practicing third-degree price discrimination, as the marginal cost of serving both groups is identical.

Award [1 mark] for selecting option C. Award [0 marks] for any other response.

1. When the public buys $50 million of government bonds from the central bank and keeps cash holding at $300 million, the purchase is settled via bank reserves. Bank reserves drop from $400 million to \(\$400 - \$50 = \$350\text{ million}\).
2. With the required reserve ratio at \(r = 25\% = 0.25\) and no excess reserves, the maximum deposits supported by the banking system become:
$$\text{Maximum Deposits} = \frac{\text{Reserves}}{r} = \frac{\$350\text{ million}}{0.25} = \$1\,400\text{ million}$$
3. Total money supply = \(\text{Cash held by the public} + \text{Total bank deposits} = \$300\text{ million} + \$1\,400\text{ million} = \$1\,700\text{ million}\).

Award [1 mark] for selecting option B. Award [0 marks] for any other response.

- An effective price ceiling is set below the equilibrium price (\(P_c < P_e\)). At \(P_c\), quantity demanded exceeds quantity supplied (\(Q_d > Q_s\)), resulting in an excess demand (shortage). Statement (1) is correct.
- The actual quantity transacted falls to \(Q_s\) (since \(Q_s < Q_e\)). Total expenditure of consumers becomes \(P_c \times Q_s\). Since \(P_c < P_e\) and \(Q_s < Q_e\), total expenditure \(P_c \times Q_s < P_e \times Q_e\). Therefore, total expenditure must decrease. Statement (2) is correct.
- Since the transacted quantity is lower than the efficient market equilibrium output (\(Q_s < Q_e\)), marginal social benefit exceeds marginal social cost for the units not produced, creating a deadweight loss and lowering total social surplus. Statement (3) is correct.

Award [1 mark] for selecting option D. Award [0 marks] for any other response.

For a small open economy imposing a tariff:
- The domestic market price rises by the amount of the tariff from \(P_w\) to \(P_w + t\).
- Domestic quantity supplied increases as domestic producers face a higher price, which unambiguously increases domestic producer surplus.
- Domestic quantity demanded falls, reducing consumer surplus and total consumption.
- Foreign exporters receive \(P_w\) per unit on a smaller import volume, so their total revenue falls.

Award [1 mark] for selecting option B. Award [0 marks] for any other response.

To determine when diminishing marginal returns set in, calculate the marginal product (\(MP\)) of each successive unit of labour:
- 1st unit: \(MP = 15 - 0 = 15\)
- 2nd unit: \(MP = 35 - 15 = 20\)
- 3rd unit: \(MP = 60 - 35 = 25\)
- 4th unit: \(MP = 80 - 60 = 20\)
- 5th unit: \(MP = 95 - 80 = 15\)
- 6th unit: \(MP = 105 - 95 = 10\)

The marginal product reaches its maximum of \(25\) units at the 3rd unit of labour and begins to decrease (from \(25\) to \(20\)) when the 4th unit of labour is employed. Therefore, the law of diminishing marginal returns sets in starting at the 4th unit of labour.

1 mark for B. No partial marks.

For third-degree price discrimination to be effective and profitable:
(1) The firm must possess monopoly/market power to set prices above marginal cost.
(2) The firm must be able to separate market sub-groups and prevent resale/arbitrage between the groups.
(3) The sub-markets must have different price elasticities of demand (the group charged the lower price, senior citizens, must have a higher price elasticity of demand).
Hence, statements (1), (2), and (3) are all necessary conditions.

1 mark for D. No partial marks.

In a small open economy, a specific tariff of $10 raises the domestic price by the full amount of the tariff (from $40 to $50). At a higher domestic price:
- Domestic quantity supplied increases, thereby increasing the producer surplus of domestic manufacturers (Option B is correct).
- The domestic price increases by exactly $10, not less (Option A is incorrect).
- Total expenditure on imports may increase, decrease, or remain unchanged depending on the price elasticity of demand for imports (Option C is incorrect).
- Deadweight loss is the net loss of social surplus, which is strictly less than or distinct from the tariff revenue collected by the government (Option D is incorrect).

1 mark for B. No partial marks.

First, calculate the opportunity cost of producing 1 bicycle in each country:
- In Country A: \(40 \text{ watches} / 20 \text{ bicycles} = 2 \text{ watches per bicycle}\).
- In Country B: \(30 \text{ watches} / 10 \text{ bicycles} = 3 \text{ watches per bicycle}\).

Country A has a lower opportunity cost in producing bicycles (\(2 < 3\)), so Country A has a comparative advantage in bicycles and exports bicycles.
Country B has a comparative advantage in watches and exports watches.

Mutually beneficial terms of trade for 1 bicycle must lie strictly between the opportunity costs of the two countries: \(2 \text{ watches} < 1 \text{ bicycle} < 3 \text{ watches}\).
Among the options, \(1 \text{ bicycle} = 2.5 \text{ watches}\) lies within this range.

1 mark for B. No partial marks.

During hyperinflation, the purchasing power of money falls extremely rapidly over time, which severely undermines the willingness of people to hold money as an asset to store wealth (store of value function is severely weakened).
- Option A is incorrect because an asset can serve simultaneously as a medium of exchange and a unit of account.
- Option B is incorrect because credit cards are a means of deferred payment/credit, not legal tender.
- Option D is incorrect because modern fiat money derives its value from government decree and social trust, not gold backing.

1 mark for C. No partial marks.

Initial Money Supply \(M_1 = \text{Deposits} + \text{Cash} = \$2\,000\text{ M} + 0 = \$2\,000\text{ M}\).

When $100 million is withdrawn in cash:
- Bank reserves decrease by $100 million to $300 million.
- Public cash holdings become $100 million.
- Maximum deposits supported by $300 million of reserves = \(\frac{\$300\text{ M}}{0.20} = \$1\,500\text{ M}\).
- New maximum money supply \(M_2 = \text{Deposits} + \text{Cash} = \$1\,500\text{ M} + \$100\text{ M} = \$1\,600\text{ M}\).

Therefore, the contraction in money supply = \(M_1 - M_2 = \$2\,000\text{ M} - \$1\,600\text{ M} = \$400\text{ M}\).

1 mark for B. No partial marks.

A profit-maximizing monopoly produces at the output level where \(MR = MC\). Since \(MC > 0\), it follows that at the profit-maximizing output, \(MR > 0\).
From the relationship between marginal revenue and price elasticity of demand: \(MR = P\left(1 - \frac{1}{|E_d|}\right)\).
For \(MR > 0\), it requires \(1 - \frac{1}{|E_d|} > 0 \implies |E_d| > 1\) (elastic region of the demand curve).
Therefore, the price elasticity of demand is greater than one.

1 mark for C. No partial marks.

Under liquidity preference theory, the equilibrium interest rate is determined by the intersection of money demand and money supply:
- An increase in real national income increases the transaction demand for money, shifting the money demand curve to the right and driving the equilibrium nominal interest rate upward (Option B is correct).
- Open market purchases of bonds increase money supply, lowering interest rates (Option A is incorrect).
- A decrease in the cash-to-deposit ratio expands credit creation and increases money supply, lowering interest rates (Option C is incorrect).
- Widespread adoption of electronic payments decreases money demand, lowering interest rates (Option D is incorrect).

1 mark for B. No partial marks.

Opportunity cost is the highest-valued alternative forgone. If Kelvin chooses to attend the concert, he forgives the opportunity to work the freelance shift (earning $1,400) and the opportunity to resell his ticket (receiving $1,600). Since both the freelance earning and the ticket resale revenue could be obtained together if he gives up attending the concert, the total value of the best alternative forgone is \(\$1,400 + \$1,600 = \$3,000\). Note that the original purchase price of \(\$900\) is a sunk cost and does not affect the decision.

Correct answer [1 mark]. Accept C only. Deduct 0 marks for incorrect options.

Calculate the marginal product (\(MP\)) of each successive unit of labour:
- 1st unit: \(MP_1 = 14\)
- 2nd unit: \(MP_2 = 32 - 14 = 18\)
- 3rd unit: \(MP_3 = 54 - 32 = 22\)
- 4th unit: \(MP_4 = 70 - 54 = 16\)
- 5th unit: \(MP_5 = 80 - 70 = 10\)

The marginal product increases up to the 3rd unit (from 18 to 22) and begins to diminish with the addition of the 4th unit of labour (falling from 22 to 16). Hence, the law sets in when the 4th unit of labour is employed.

Correct answer [1 mark]. Accept C only.

For third-degree price discrimination to occur and be profitable:
(1) The firm must possess market power to set different prices.
(2) The group charged the higher price (overseas visitors) must have a lower price elasticity of demand (less price-sensitive), not higher.
(3) Arbitrage/resale between customer sub-markets must be preventable.
Therefore, only statements (1) and (3) are correct.

Correct answer [1 mark]. Accept B only.

Opportunity cost of producing 1 unit of Watches:
- Country A: \(20 / 10 = 2\) units of Toys
- Country B: \(32 / 8 = 4\) units of Toys
Country A has a lower opportunity cost in producing Watches, so it exports Watches. Country B has a lower opportunity cost in producing Toys (\(8/32 = 0.25\) Watches vs \(10/20 = 0.5\) Watches) and exports Toys.
For mutually beneficial trade, the terms of trade for 1 unit of Watches must lie strictly between the domestic opportunity costs of the two countries: \(2\text{ Toys} < 1\text{ Watch} < 4\text{ Toys}\). Thus, 1 unit of Watches = 3 units of Toys is mutually beneficial.

Correct answer [1 mark]. Accept B only.

The initial deposits are \(\$2,000\text{ million}\). After \(\$200\text{ million}\) of cash is deposited, the total reserves become \(\$500\text{ million} + \$200\text{ million} = \$700\text{ million}\).
With a required reserve ratio of 20% (0.20) and no excess reserves or cash leakages, the maximum possible deposits are:
$$\text{Maximum Deposits} = \frac{\text{Total Reserves}}{\text{Required Reserve Ratio}} = \frac{\$700\text{ million}}{0.20} = \$3,500\text{ million}$$
The maximum increase in total deposits is:
$$\Delta\text{Deposits} = \$3,500\text{ million} - \$2,000\text{ million} = \$1,500\text{ million}$$

Correct answer [1 mark]. Accept D only.

Total expenditure \(TE = P \times Q\). When price \(P\) decreases and total expenditure \(TE\) increases, price and total expenditure move in opposite directions, which indicates that demand is elastic (\(|E_d| > 1\)). Thus statement (1) is correct.
For total revenue to rise despite a 10% fall in price, the percentage increase in quantity demanded must be strictly greater than the percentage decrease in price (i.e. \(\%\Delta Q > 10\%\)), making statement (2) correct.
Normal vs inferior goods depend on income elasticity of demand, not price elasticity of demand; thus statement (3) cannot be deduced.

Correct answer [1 mark]. Accept A only.

Equilibrium without quota: \(P = \$20\), \(Q = 100\).
With a quota of 70 units:
- Quantity transacted \(Q_t = 70\).
- Buyers are willing to pay \(P_d = \$25\) for 70 units.
- Sellers require a supply price of \(P_s = \$15\) for 70 units.
Market price equals \(\$25\).
Deadweight loss is the triangle area representing lost surplus on the \(100 - 70 = 30\) units not traded:
$$\text{Deadweight Loss} = \frac{1}{2} \times (P_d - P_s) \times \Delta Q = \frac{1}{2} \times (\$25 - \$15) \times (100 - 70) = \frac{1}{2} \times 10 \times 30 = \$150$$

Correct answer [1 mark]. Accept B only.

An increase in labour productivity reduces production costs and shifts the short-run aggregate supply curve (SRAS) to the right.
A decline in consumer confidence reduces private consumption expenditure and shifts the aggregate demand curve (AD) to the left.
- Effect on price level: Both a rightward shift of SRAS and a leftward shift of AD put downward pressure on the price level, so the price level will definitely decrease.
- Effect on real output: A rightward shift of SRAS tends to increase real output, while a leftward shift of AD tends to decrease real output. The combined effect on real output is ambiguous (may increase, decrease, or remain unchanged).

Correct answer [1 mark]. Accept B only.

To find comparative advantage, calculate the opportunity cost for each country:
- In Country X: The opportunity cost of 1 unit of smart watches is \(4 / 8 = 0.5\) units of tablets. The opportunity cost of 1 unit of tablets is \(8 / 4 = 2\) units of smart watches.
- In Country Y: The opportunity cost of 1 unit of smart watches is \(6 / 9 = 0.67\) units of tablets. The opportunity cost of 1 unit of tablets is \(9 / 6 = 1.5\) units of smart watches.

Country X has a lower opportunity cost in producing smart watches (\(0.5 < 0.67\)), so it has a comparative advantage in smart watches.
Country Y has a lower opportunity cost in producing tablets (\(1.5 < 2\)), so it has a comparative advantage in tablets.

Mutually beneficial terms of trade for 1 unit of tablets must lie between \(1.5\) and \(2\) units of smart watches (or \(1\) unit of smart watches exchanged for between \(0.5\) and \(0.67\) units of tablets).
Therefore, Country Y will export tablets and mutually beneficial terms of trade can be 1 unit of tablets for 1.8 units of smart watches.

B (1 mark)
- Award 1 mark for the correct option B.
- No mark for A, C, or D.

1. Required reserve ratio \(r = \frac{\text{Reserves}}{\text{Deposits}} = \frac{500}{2\,500} = 20\% = 0.2\).
2. Initial money supply \(M_1 = \text{Cash held by public} + \text{Deposits} = 400 + 2\,500 = 2\,900\text{ million}\).
3. When the public withdraws $100\text{ million} cash:
- New cash held by public = \(400 + 100 = 500\text{ million}\).
- Remaining bank reserves = \(500 - 100 = 400\text{ million}\).
- New maximum deposits = \(\frac{400}{0.2} = 2\,000\text{ million}\).
4. New money supply \(M_2 = 500 + 2\,000 = 2\,500\text{ million}\).
5. Change in money supply = \(2\,500 - 2\,900 = -400\text{ million}\) (i.e. decreases by $400\text{ million}).

C (1 mark)
- Correct answer C: a decrease of $400 million.
- Incorrect choices: A (-$500 million), B (-$450 million), D (-$100 million).

For third-degree price discrimination:
- Condition (1) is correct: To maximise profit, the firm charges a higher price in the sub-market with lower price elasticity of demand.
- Condition (2) is incorrect: Price discrimination involves charging different prices for the same service that do not reflect differences in production/marginal costs. The marginal cost of serving both groups is the same.
- Condition (3) is correct: Arbitrage/resale between customer groups must be prevented for price discrimination to be viable.

Hence, statements (1) and (3) are correct.

B (1 mark)
- Award 1 mark for choosing B: (1) and (3) only.

Calculate the Marginal Product (MP) of each successive unit of labour:
- 1st unit: \(MP_1 = 18\)
- 2nd unit: \(MP_2 = 40 - 18 = 22\)
- 3rd unit: \(MP_3 = 66 - 40 = 26\)
- 4th unit: \(MP_4 = 86 - 66 = 20\)
- 5th unit: \(MP_5 = 100 - 86 = 14\)

Diminishing marginal returns begins when the marginal product starts to decline, which occurs when the 4th unit of labour is employed (as MP drops from 26 to 20).

A (1 mark)
- Award 1 mark for option A.

1. Equilibrium without intervention: \(P^* = \$50\), \(Q^* = 120\) units.
2. Initial total expenditure by consumers = \(50 \times 120 = \$6\,000\).
3. With a price ceiling at $40:
- Quantity demanded \(Q_d = 140\) units.
- Quantity supplied \(Q_s = 90\) units.
- Actual transacted quantity \(Q = 90\) units.
- Shortage = \(140 - 90 = 50\) units.
- New total expenditure by consumers = \(40 \times 90 = \$3\,600\).
- Total expenditure decreases by \(6\,000 - 3\,600 = \$2\,400\).
4. Option A is incorrect because the transacted quantity is 90 units, not 140 units.
5. Option B is incorrect because there is an excess demand (shortage) of 50 units.
6. Option C is incorrect because total expenditure decreases from $6\,000 to $3\,600.

D (1 mark)
- Award 1 mark for option D.

(a) The law of diminishing marginal returns states that as successive units of a variable factor are added to a given quantity of fixed factors, the marginal product of the variable factor will eventually decrease, holding technology and all other factors constant.

(b) Marginal Product (MP) of each successive worker:
- 1st worker: \(14 - 0 = 14\) units
- 2nd worker: \(32 - 14 = 18\) units
- 3rd worker: \(54 - 32 = 22\) units
- 4th worker: \(72 - 54 = 18\) units
- 5th worker: \(85 - 72 = 13\) units

Since the marginal product reaches its maximum at the 3rd unit of labour (22 units) and begins to decline continuously from the 4th unit of labour onwards (falling to 18 units and then 13 units), the law of diminishing marginal returns is clearly illustrated by the data.

(a)
- States that when variable factors are continuously added to fixed factors (1 mark)
- Marginal product of the variable factor will eventually decline, ceteris paribus (1 mark)

(b)
- Correct calculation/listing of marginal products for all units of labour (1.5 marks)
- Identifies that marginal product starts to decrease when the 4th unit of labour is employed (from 22 to 18) (1 mark)
- Concludes that the data illustrates the law (1 mark)

(a) Two advantages of converting to a private limited company:
1. Limited Liability: Under a partnership, partners have unlimited liability. As a private limited company, owners enjoy limited liability, meaning their personal assets are protected up to the amount of their capital contribution/unpaid shares in case of business liquidation.
2. Separate Legal Entity / Continuity: The company becomes a separate legal entity from its owners, allowing the business to enjoy perpetual succession; the withdrawal, retirement, or demise of a shareholder does not force the firm into dissolution.

(b) One disadvantage compared to a public limited company:
- A private limited company cannot issue shares or debentures to the general public or be listed on the stock exchange, which restricts its ability to raise large sums of capital for expansion.

(a)
- Advantage 1 (Limited liability explained): 2 marks (1 mark for stating limited liability, 1 mark for explaining protection of personal assets)
- Advantage 2 (Separate legal entity / perpetual succession / wider source of capital relative to partnership): 1.5 marks

(b)
- Disadvantage compared to public limited company (Cannot invite general public to subscribe to shares / lower capital raising ability): 2 marks

(a) An externality exists because the factory imposes an uncompensated external cost on nearby residents due to the noxious fumes. Consequently:
$$\text{Marginal Social Cost (MSC)} = \text{Marginal Private Cost (MPC)} + \text{Marginal External Cost (MEC)}$$
Since \(\text{MEC} > 0\), \(\text{MSC} > \text{MPC}\). In a free market without intervention, the factory produces where \(\text{Marginal Private Benefit (MPB)} = \text{MPC}\). However, the socially efficient level of output requires \(\text{MSB} = \text{MSC}\). Because \(\text{MSC} > \text{MPC}\), output is over-produced relative to the efficient level, resulting in an inefficiency / deadweight loss.

(b) The government could impose a per-unit corrective tax (Pigouvian tax) on the factory's output equal to the marginal external cost. This internalizes the external cost, shifting the private supply curve up to coincide with the social cost curve.

(a)
- Defines/identifies negative externality / external cost on residents without compensation (1 mark)
- States \(\text{MSC} > \text{MPC}\) or \(\text{MSC} = \text{MPC} + \text{external cost}\) (1.5 marks)
- Explains that free-market output is higher than socially optimal output (over-production/inefficiency) (1 mark)

(b)
- Suggests an appropriate policy (e.g., per-unit tax / emission tax / production quota) and explains how it internalizes external cost / eliminates divergence (2 marks)

(a) The functions of money that Z-dollars failed to perform are:
1. Unit of account (measure of value): Merchants refuse to quote prices in Z-dollars.
2. Standard of deferred payment: Long-term contracts and loan repayments are no longer settled in Z-dollars.

(b) During hyperinflation, the general price level rises at an extremely rapid pace, drastically eroding the real purchasing power of paper fiat money because the money supply grows uncontrollably. In contrast, gold is a physical commodity with intrinsic worth and limited physical supply that cannot be arbitrarily inflated by the monetary authority. Therefore, gold preserves purchasing power and serves as a far superior store of value.

(a)
- Identifies unit of account / measure of value (1 mark)
- Identifies standard of deferred payment (1 mark)
(Accept medium of exchange if appropriately linked to refusal of acceptance in transactions)

(b)
- Explains that hyperinflation rapidly erodes the purchasing power of fiat currency (2 marks)
- Explains that gold has limited physical supply / intrinsic value and retains purchasing power over time (1.5 marks)

(a)
$$\text{Labour Force} = \text{Employed population} + \text{Unemployed population}$$
$$\text{Labour Force} = 3\,680\,000 + 120\,000 = 3\,800\,000$$

$$\text{Unemployment Rate} = \frac{\text{Unemployed population}}{\text{Labour Force}} \times 100\%$$
$$\text{Unemployment Rate} = \frac{120\,000}{3\,800\,000} \times 100\% \approx 3.16\%$$

(b) Discouraged workers are not actively seeking employment and are therefore classified as outside the labour force. When 30,000 unemployed individuals stop seeking jobs, both the numerator (number of unemployed persons) and the denominator (total labour force) decrease by 30,000:
$$\text{New Unemployment Rate} = \frac{120\,000 - 30\,000}{3\,800\,000 - 30\,000} \times 100\% = \frac{90\,000}{3\,770\,000} \times 100\% \approx 2.39\%$$
Hence, the official unemployment rate will decrease.

(a)
- Identifies correct formula / calculation of labour force as \(3\,800\,000\) (1 mark)
- Correct calculation of unemployment rate: \(3.16\%\) (1.5 marks)

(b)
- Explains that discouraged workers leave the labour force (1 mark)
- Identifies that both unemployed population and labour force decrease by 30,000 (1 mark)
- Concludes that the unemployment rate decreases (1 mark)

(a)
$$\text{Required Reserve Ratio } (rr) = \frac{\text{Required Reserves}}{\text{Total Deposits}} = \frac{\$800\text{ million}}{\$4\,000\text{ million}} = 0.20 = 20\%$$

(b) When the public deposits $200 million in cash:
- Cash held by the non-bank public decreases by $200 million: \(\Delta C_p = -\$200\text{ million}\).
- Bank reserves increase by $200 million: \(\Delta R = +\$200\text{ million}\).
- The maximum expansion in total bank deposits is:
$$\Delta D = \frac{\Delta R}{rr} = \frac{+\$200\text{ million}}{0.20} = +\$1\,000\text{ million}$$

Money supply (\(M\)) consists of currency in public circulation (\(C_p\)) plus total deposits (\(D\)):
$$\Delta M = \Delta C_p + \Delta D = -\$200\text{ million} + \$1\,000\text{ million} = +\$800\text{ million}$$
Thus, the maximum possible increase in money supply is $800 million.

(a)
- Correct formula and calculation of required reserve ratio = 20% (1.5 marks)

(b)
- Calculation of maximum change in deposits: \(+\$1\,000\text{ million}\) (1.5 marks)
- Accounting for the change in cash held by public: \(-\$200\text{ million}\) (1.5 marks)
- Final change in money supply: \(+\$800\text{ million}\) (1 mark)

(a) The principle of comparative advantage states that a country should specialize in producing and exporting goods that it can produce at a lower opportunity cost compared to other trading partners.

(b) Opportunity costs of production:
- In Country H:
$$\text{Opportunity cost of 1 unit of watches} = \frac{30}{60} = 0.5\text{ units of shoes}$$
$$\text{Opportunity cost of 1 unit of shoes} = \frac{60}{30} = 2\text{ units of watches}$$
- In Country K:
$$\text{Opportunity cost of 1 unit of watches} = \frac{40}{40} = 1\text{ unit of shoes}$$
$$\text{Opportunity cost of 1 unit of shoes} = \frac{40}{40} = 1\text{ unit of watches}$$

Country H incurs an opportunity cost of only 0.5 units of shoes to produce 1 watch, which is lower than Country K's opportunity cost of 1 unit of shoes per watch. Therefore, Country H has a comparative advantage in producing watches and should specialize in and export watches.

(a)
- States that a country should specialize in/export the good with a lower opportunity cost (2 marks)

(b)
- Calculation of opportunity cost for Country H (0.5 units of shoes per watch) (1 mark)
- Calculation of opportunity cost for Country K (1 unit of shoes per watch) (1 mark)
- Comparison showing Country H has a lower opportunity cost in producing watches (0.5 < 1) (1 mark)
- Concludes Country H exports watches (0.5 mark)

(a) For a small open economy:
- Domestic price: The tariff raises the domestic selling price from the world price \(P_w\) to \(P_w + t\).
- Domestic production: As the domestic price rises, domestic producers move along their upward-sloping supply curve, increasing domestic output from \(Q_{s1}\) to \(Q_{s2}\).
- Import volume: The quantity demanded domestically falls due to the price increase, while domestic supply rises. Since \(\text{Imports} = Q_d - Q_s\), the volume of imported wheat contracts.

(b) No, an increase in the tariff rate will not necessarily increase tariff revenue:
- Tariff revenue is calculated as \(\text{Tariff per unit} \times \text{Import quantity}\).
- If the tariff rate is raised significantly, import volume will fall. If the percentage decrease in import volume is larger than the percentage increase in the tariff rate (e.g., when domestic demand and supply are price elastic, or if the tariff is prohibitive and drives imports to zero), total tariff revenue will decrease.

(a)
- Domestic price increases by the amount of tariff / to \(P_w + t\) (1 mark)
- Domestic production increases (1 mark)
- Import volume decreases (1.5 marks)

(b)
- States not necessarily / no (0.5 mark)
- Explains that tariff revenue = \(\text{tariff rate} \times \text{quantity of imports}\) and a large drop in imports can offset the higher tax rate (1.5 marks)

(a) The principle of comparative advantage states that a country should specialize in producing and exporting the good in which it has a lower opportunity cost.

(b) (i)
- Country H: Opportunity cost of 1 unit of Wind Turbine = \(\frac{20}{10} = 2\text{ units of Solar Panels}\).
- Country F: Opportunity cost of 1 unit of Wind Turbine = \(\frac{45}{15} = 3\text{ units of Solar Panels}\).
(ii) Country H has a lower opportunity cost in producing Wind Turbines (2 Solar Panels < 3 Solar Panels). According to the principle of comparative advantage, Country H will specialize in and export Wind Turbines.

(c) (i)
- Each country pays half of the transport cost, which is \(0.2 / 2 = 0.1\text{ units of Solar Panels}\).
- Country H (exporter of Wind Turbines): Receives 2.5 Solar Panels, pays 0.1 Solar Panels for transport, net revenue = 2.4 Solar Panels. Gain per unit = \(2.4 - 2.0 = 0.4\text{ units of Solar Panels}\).
- Country F (importer of Wind Turbines): Pays 2.5 Solar Panels + 0.1 transport cost = 2.6 Solar Panels. Domestic opportunity cost = 3.0 Solar Panels. Gain per unit = \(3.0 - 2.6 = 0.4\text{ units of Solar Panels}\).
(ii) Yes, trade is still feasible because both countries enjoy a positive net gain (0.4 units of Solar Panels each).

(d) (i)
- The tariff increases the domestic market price of imported Solar Panels in Country H.
- Due to the higher domestic price, domestic quantity demanded falls while domestic quantity supplied (domestic production) increases.
- The import volume (gap between quantity demanded and domestic supply) decreases.
(ii)
- Initially, the tariff reduces import expenditure on Solar Panels, improving the merchandise trade balance and current account balance.
- However, if trading partners retaliate by imposing tariffs on Country H's exports (e.g., Wind Turbines), export revenue of Country H will fall, which may worsen the current account balance.

(a)
- Stating that a country specializes in/exports the good with a lower opportunity cost. [2 marks]

(b)(i)
- Opportunity cost in Country H = 2 units of Solar Panels. [1 mark]
- Opportunity cost in Country F = 3 units of Solar Panels. [1 mark]

(b)(ii)
- Stating that Country H has a lower opportunity cost in producing Wind Turbines. [1 mark]
- Country H will specialize in and export Wind Turbines. [1 mark]
- Application of comparative advantage principle. [1 mark]

(c)(i)
- Allocation of transportation cost = 0.1 units of Solar Panels per country. [1 mark]
- Net gain of Country H = 0.4 units of Solar Panels. [1 mark]
- Net gain of Country F = 0.4 units of Solar Panels. [1 mark]

(c)(ii)
- Explaining that trade remains mutually beneficial as both countries gain. [2 marks]

(d)(i)
- Domestic price increases. [1 mark]
- Domestic production increases. [1 mark]
- Domestic quantity demanded decreases / import volume shrinks. [2 marks]

(d)(ii)
- Initial reduction in import expenditure improves the current account balance. [2 marks]
- Potential retaliation causes export revenue to fall, potentially deteriorating the current account balance. [2 marks]

(a) (i) Required reserve ratio \(r = \frac{\text{Reserves}}{\text{Deposits}} = \frac{800}{4000} = 20\%\) (or 0.2).
(ii)
- Monetary base \(B = \text{Cash held by public} + \text{Bank reserves} = 400 + 800 = \$1\,200\text{ million}\).
- Money supply \(M = \text{Cash held by public} + \text{Deposits} = 400 + 4000 = \$4\,400\text{ million}\).

(b) (i)
- Public receives $160\text{ million}\), deposits \(75\% \times 160 = \$120\text{ million}\).
- New total bank reserves = \(800 + 120 = \$920\text{ million}\).
(ii)
- Total bank reserves = $920\text{ million}\).
- Maximum deposits supported = \(\frac{\text{Reserves}}{r} = \frac{920}{0.2} = \$4\,600\text{ million}\).
- Total new deposits created = \(4\,600 - 4\,000 = \$600\text{ million}\).
(iii)
- Final cash held by public = \(400 + (25\% \times 160) = 400 + 40 = \$440\text{ million}\).
- Final money supply = \(440 + 4\,600 = \$5\,040\text{ million}\).
- Change in money supply = \(5\,040 - 4\,400 = +\$640\text{ million}\).

(c) (i)
1. Velocity of money (\(V\)) is constant/stable.
2. Real output (\(Y\)) is determined by real factors / fixed at full-employment output level in the long run.
(ii)
- Percentage change equation: \(\%\Delta M + \%\Delta V = \%\Delta P + \%\Delta Y\).
- \(7\% + 0\% = \%\Delta P + 2\% \implies \%\Delta P = 5\%\).
- The inflation rate is 5%.

(d)
- In the short run, the open market bond purchase increases money supply and lowers the nominal interest rate.
- Lower interest rate stimulates investment expenditure and consumption expenditure, causing Aggregate Demand (AD) to shift rightward from \(AD_0\) to \(AD_1\).
- In the AD-AS diagram with an upward-sloping SRAS curve, the price level increases from \(P_0\) to \(P_1\) and real output increases above the full-employment level from \(Y_0\) to \(Y_1\) (inflationary output gap).

(a)(i)
- Correct calculation of \(r = 20\%\). [1 mark]

(a)(ii)
- Monetary base = $1,200 million. [1 mark]
- Money supply = $4,400 million. [1 mark]

(b)(i)
- Increase in bank reserves = $120 million, total reserves = $920 million. [2 marks]

(b)(ii)
- Formula/working for maximum deposits: \(D = \frac{\text{Reserves}}{r} = \frac{920}{0.2} = \$4,600\text{ million}\). [2 marks]
- Net increase in deposits = $600 million. [2 marks]

(b)(iii)
- New cash held by public = $440 million. [1 mark]
- New money supply = $5,040 million. [1 mark]
- Change in money supply = +$640 million. [1 mark]

(c)(i)
- Any TWO valid assumptions (constant velocity \(V\), real output \(Y\) fixed at potential output). [2 marks]

(c)(ii)
- Correct application of equation: \(7\% - 2\% = 5\%\). [2 marks]

(d)
- Correct diagram showing AD curve shifting rightward, higher price level and higher real output. [2 marks]
- Verbal explanation linking money supply increase to interest rate fall, AD expansion, and resulting increase in price level and output in the short run. [2 marks]

(a)
1. High initial capital cost / economies of scale: Constructing railway tracks and purchasing trains require huge initial capital expenditure. The average total cost declines continuously over a very large range of output (natural monopoly).
2. Government franchise / legal barriers: The government may grant exclusive statutory rights or licenses to a single company to operate railway services on specific routes.

(b) (i)
1. The firm must possess market power (price-setting power).
2. The firm can identify and separate different consumer groups with different price elasticities of demand.
3. Resale or arbitrage between the two markets can be prevented at a low cost.

(ii)
- Local Commuters have more accessible substitutes (e.g., public buses, carpooling) and travel regularly, making their demand for airport railway tickets more price-elastic.
- Tourists are less familiar with alternative transport options and place a higher value on travel time/convenience, making their demand more price-inelastic.
- To maximize total revenue/profits, the monopolist charges a lower price to the market with higher price elasticity of demand (Local Commuters) and a higher price to the market with lower price elasticity of demand (Tourists).

(c) (i)
- Allocative efficiency is achieved when price equals marginal cost (\(P = MC\)).
- Price represents the marginal social benefit (MSB) to consumers, and marginal cost represents the marginal social cost (MSC) of production.
- When \(P = MC\), \(MSB = MSC\), and total social surplus is maximized with zero deadweight loss.

(ii)
- If the firm experiences significant economies of scale, marginal cost lies below average total cost (\(MC < ATC\)). Setting \(P = MC\) results in \(P < ATC\), causing the operator to suffer continuous subnormal profits (losses) and possibly exit without subsidies.

(iii)
- Fiscal expenditure:
- Option 1 (Price ceiling): Does not involve direct government spending or subsidies, so it places zero burden on the government fiscal budget (unless subsidies are needed to cover losses).
- Option 2 (Per-unit subsidy): Requires direct financial outlays from the government budget, which increases government spending and may worsen fiscal deficit or require higher taxes elsewhere.
- Consumer welfare:
- Option 1 directly lowers ticket prices to marginal cost, directly increasing consumer surplus and preventing monopoly markup.
- Option 2 lowers the firm's marginal cost curve, but because the firm still has monopoly power, it will only pass on part of the subsidy to consumers depending on elasticity, leading to smaller consumer welfare gains compared to direct marginal cost regulation unless heavily regulated.

(a)
- First reason explained clearly (e.g., economies of scale / large initial fixed capital). [2 marks]
- Second reason explained clearly (e.g., legal barrier / government franchise / control of critical network infrastructure). [2 marks]

(b)(i)
- Stating market power. [1 mark]
- Stating market segmentation / differing elasticities. [1 mark]
- Stating prevention of resale / arbitrage. [1 mark]

(b)(ii)
- Identifying that Local Commuters have higher price elasticity of demand due to substitutes/routine travel. [1 mark]
- Identifying that Tourists have lower price elasticity of demand. [1 mark]
- Explaining the profit-maximizing pricing rule relating higher elasticity to lower price. [1 mark]

(c)(i)
- Explaining \(P = MC\) implies \(MSB = MSC\). [2 marks]
- Explaining that total social surplus is maximized / deadweight loss is eliminated. [1 mark]

(c)(ii)
- Identifying that \(MC < ATC\) under natural monopoly causes economic losses (\(P < ATC\)). [2 marks]

(c)(iii)
- Comparison on government fiscal expenditure: Option 1 incurs no fiscal outlay; Option 2 creates fiscal burden/spending. [2 marks]
- Comparison on consumer welfare: Option 1 directly eliminates monopoly pricing markup; Option 2 only partially reduces prices as monopolist retains pricing power. [2 marks]
- Logical conclusion/overall evaluation. [1 mark]

(a) (i) To maximise profit, Ocean Express produces output at the level where marginal revenue equals marginal cost (\( \text{MR} = \text{MC} \)), and sets the price based on the market demand curve (average revenue curve) at this output level.

(ii) Under uniform pricing, the profit-maximising output \( Q_m \) is lower than the efficient output \( Q_e \) (where \( P = \text{MC} \)). For units of output between \( Q_m \) and \( Q_e \), marginal benefit (price) exceeds marginal cost (\( P > \text{MC} \)), but these units are not produced. This leads to an underproduction of ferry services and a net loss of total social surplus, known as deadweight loss.

Diagram representation:
- Downward sloping demand curve (\( D = \text{AR} \)) and marginal revenue curve (\( \text{MR} \)) below \( D \).
- Upward sloping or horizontal marginal cost curve (\( \text{MC} \)).
- Monopoly output \( Q_m \) at \( \text{MR} = \text{MC} \) and monopoly price \( P_m \) on the demand curve.
- Efficient output \( Q_e \) where demand intersects \( \text{MC} \).
- Shaded deadweight loss triangle between \( Q_m \) and \( Q_e \), bounded by the demand curve and \( \text{MC} \) curve.

(b) (i) Price discrimination refers to the practice of selling the same good or service at different prices to different buyers, where the price differences are not caused by differences in production costs. Here, both senior citizens and adults receive identical ferry transport services in the same cabin class (incurring the same cost to provide), but are charged different prices ($40 vs $80).

(ii) Two conditions:
1. The firm must possess market power (price-setting power) / be a price searcher.
2. The firm can effectively separate the market into distinct sub-markets and prevent resale/arbitrage between passenger groups (e.g., verifying age through identity cards/Elderly Octopus cards).

(iii) Senior citizens generally have higher price elasticity of demand for ferry trips than working adults because senior citizens have more flexible schedules / lower opportunity cost of time / lower income, whereas working adult commuters have fixed travel schedules and urgent commuting needs (lower price elasticity). Profit-maximising third-degree price discrimination dictates charging a lower price to the group with higher price elasticity of demand.

(c) (i) Predatory pricing.

(ii) Conduct Rule: The Second Conduct Rule.
Conditions to establish a breach:
1. The undertaking (firm) has a substantial degree of market power in the relevant market.
2. The undertaking abuses that market power by engaging in conduct that has the object or effect of preventing, restricting, or distorting competition in Hong Kong.

(a) (i) Profit-maximisation rule: \( \text{MR} = \text{MC} \) (1 mark).
(ii) Explanation of deadweight loss (underproduction where \( P > \text{MC} \), loss of total social surplus) (1 mark).
Diagram:
- Correct demand curve, \( \text{MR} \) curve, and \( \text{MC} \) curve with correct identification of \( Q_m \), \( P_m \), and \( Q_e \) (2 marks).
- Correct shaded area of deadweight loss (1 mark).
[Total: 5 marks]

(b) (i) Definition of price discrimination: same product sold at different prices not due to cost differences (1 mark); application to this case (same cabin/route at different fares not due to cost differences) (2 marks).
[Total: 3 marks]
(ii) Any TWO conditions (1 mark each):
- Market/monopoly power (price-setting ability).
- Ability to segment the market and prevent resale/arbitrage.
[Total: 2 marks]
(iii) Explanation: Senior citizens have a higher price elasticity of demand (more elastic) than adults (1 mark), so setting a lower price for the more elastic group maximises total profit (1 mark).
[Total: 2 marks]

(c) (i) Predatory pricing (1 mark).
(ii) Second Conduct Rule (1 mark).
TWO conditions (1 mark each):
- The firm possesses a substantial degree of market power in the market (1 mark).
- The conduct has the object or effect of preventing, restricting, or distorting competition (1 mark).
[Total: 4 marks]