2023 HKDSE Economics Answers & Marking Scheme

Country A's opportunity cost of producing 1 Computer is 2 Toys (20/10). Country B's opportunity cost of producing 1 Computer is 3 Toys (45/15). For mutually beneficial trade, the price of 1 Computer must lie between 2 Toys and 3 Toys. Therefore, 1 Computer = 2.5 Toys is a mutually beneficial terms of trade.

Correct answer is B (1 mark). Other options represent terms of trade outside the mutually beneficial range.

A decrease in the required reserve ratio increases the money supply, which exerts a downward pressure on the interest rate. An increase in the income tax rate reduces disposable income and consumption, shifting the aggregate demand (AD) curve to the left and lowering real GDP, which also reduces the transaction demand for money, further lowering the interest rate. Thus, the interest rate must decrease. Since the money supply expansion increases AD while the tax hike reduces AD, the net effect on real GDP is uncertain.

Correct answer is A (1 mark). Award 1 mark for identifying the correct directions of change for interest rate and real GDP.

Original Total Revenue (TR) = $20 * 50,000 = $1,000,000. New TR = $24 * 45,000 = $1,080,000. Since the price increased and the total revenue increased, the demand is price-inelastic. Alternatively, the percentage change in price is +20% and the percentage change in quantity demanded is -10%. Since % change in Qd < % change in P, demand is price-inelastic.

Correct answer is A (1 mark). Correctly calculating the TR and concluding the elasticity level.

Unexpected inflation reduces the real value of fixed nominal payments. The tenant pays a fixed nominal rent, which means the real cost of his housing expenses decreases as the general price level rises. Thus, the tenant gains. The other options involve receiving fixed nominal payments (pension, fixed interest payments, or bond coupons) and will lose purchasing power.

Correct answer is C (1 mark). Real purchasing power analysis of fixed receipts vs. fixed payments.

Let's calculate the marginal product (MP) of each unit of labor:
- 1st unit: MP = 10
- 2nd unit: MP = 22 - 10 = 12
- 3rd unit: MP = 36 - 22 = 14
- 4th unit: MP = 46 - 36 = 10
- 5th unit: MP = 54 - 46 = 8
Since MP increases up to the 3rd unit (from 12 to 14) and starts to decrease at the 4th unit (from 14 to 10), the law of diminishing marginal returns begins to set in at the 4th unit of labor.

Correct answer is C (1 mark). MP calculation must show a decrease from the peak.

Opportunity cost is the value of the highest-valued option foregone. The $400 spent on the concert ticket is a non-refundable sunk cost, which should be ignored in decision-making. Since her friend offered her a free movie ticket, the movie option now costs $0 out-of-pocket and is her highest-valued alternative option foregone (second preference). Thus, the opportunity cost of attending the concert is simply the value of watching the movie.

Correct answer is A (1 mark). Recognizing that sunk cost is excluded and the movie is the next best option.

Under an effective price ceiling, there is a shortage because quantity demanded (Qd) exceeds quantity supplied (Qs). The quantity transacted is determined by the shorter side of the market, which is Qs at the price ceiling. When demand increases (the demand curve shifts to the right), Qd at the price ceiling increases further, while Qs remains unchanged. Therefore, the shortage (Qd - Qs) increases, while the quantity transacted (Qs) remains unchanged.

Correct answer is B (1 mark). Explanation of short-side principle under price ceiling.

A major technological breakthrough increases overall productivity, which shifts both the short-run aggregate supply (SRAS) and long-run aggregate supply (LRAS) curves to the right. In the AD-AS model, a rightward shift in SRAS along a downward-sloping aggregate demand (AD) curve leads to a decrease in the equilibrium price level and an increase in real GDP in the short run.

Correct answer is A (1 mark). Analyzing shifts in the AS curve and the resulting changes on P and Y.

In a closed economy, Net exports (NX) = 0. Under the expenditure approach, GDP at market prices = C + I + G + NX = 500 + 150 + 100 + 0 = 750 million. Depreciation, indirect taxes, and subsidies are not used in calculating GDP at market prices using the expenditure approach.

Correct answer is B (1 mark). Using the expenditure approach formula correctly.

Since the HKD is pegged to the USD, any depreciation of the USD against the JPY means the HKD also depreciates against the JPY. As the HKD depreciates against the JPY, Japanese goods become more expensive in terms of HKD, so their prices in Hong Kong will likely rise. Hong Kong imports from Japan become more expensive, and Japanese tourists will find Hong Kong cheaper to visit, so their number is likely to increase.

Correct answer is C (1 mark). Analyzing exchange rate link and import prices.

To find the opportunity cost of attending the concert, we must identify the highest-valued alternative option forgone.
If he does not attend the concert, he can resell the ticket for \$180.
Therefore, the net value of his alternatives including the cash from the resold ticket is:
- Watching the movie: Valuation (\$250) - Ticket cost (\$100) + Ticket resale value (\$180) = \$330.
- Working overtime: Earnings (\$150) + Ticket resale value (\$180) = \$330.
Both options yield a net value of \$330. Thus, the opportunity cost of attending the concert is \$330.

Award 1 mark for the correct answer C. No marks for other options.

A subsidy to operators shifts the supply curve downwards/to the right. This leads to a decrease in the market price paid by consumers and an increase in the quantity transacted. Since demand is price inelastic, the percentage decrease in price is larger than the percentage increase in quantity demanded, causing consumer spending to decrease. On the other hand, the net price received by operators (market price + subsidy) increases, and quantity transacted also increases, so the total revenue of operators (including the subsidy) must increase.

Award 1 mark for the correct answer C. No marks for other options.

Shortage is the difference between quantity demanded and quantity supplied at the price ceiling. If both demand and supply are more price inelastic (steeper curves), for a given price drop from the equilibrium level, the increase in quantity demanded and the decrease in quantity supplied will be smaller. Therefore, the shortage will be smaller.

Award 1 mark for the correct answer B. No marks for other options.

Let's calculate the marginal product (MP) for each worker:
- 1st worker: MP = 10
- 2nd worker: MP = 22 - 10 = 12
- 3rd worker: MP = 36 - 22 = 14
- 4th worker: MP = 46 - 36 = 10
- 5th worker: MP = 52 - 46 = 6
Since MP increases up to the 3rd worker (14 units) and starts to decrease with the 4th worker (10 units), the law of diminishing marginal returns sets in when the 4th worker is employed.

Award 1 mark for the correct answer B. No marks for other options.

Let's calculate opportunity costs:
- In Country A, opportunity cost of 1 unit of clothing = 4/2 = 2 units of food. Opportunity cost of 1 unit of food = 2/4 = 0.5 units of clothing.
- In Country B, opportunity cost of 1 unit of clothing = 6/5 = 1.2 units of food. Opportunity cost of 1 unit of food = 5/6 = 0.83 units of clothing.
Country B has a comparative advantage in clothing (1.2 < 2 food). Country A has a comparative advantage in food (0.5 < 0.83 clothing).
Mutually beneficial terms of trade for 1 unit of clothing must lie between 1.2 and 2 units of food. Since 1.5 units of food lies within this range, both countries can gain from trade.

Award 1 mark for the correct answer C. No marks for other options.

To curb high inflation, the government needs contractionary policies that reduce aggregate demand (AD). To reduce a budget deficit, fiscal policies must either increase government revenue or decrease government expenditure.
- Increasing the corporate profits tax rate is contractionary (reduces AD) and increases government revenue (reduces deficit).
- Decreasing government transfer payments is contractionary (reduces AD) and decreases government expenditure (reduces deficit).
Therefore, Option A achieves both goals.

Award 1 mark for the correct answer A. No marks for other options.

Unexpected inflation is 3% (5% - 2%). Under unexpected inflation, real wealth is redistributed from creditors to debtors, and from landlords to tenants if lease terms are fixed.
- A tenant with a fixed nominal rent pays less in real terms than expected, thus gaining.
- A creditor with a fixed nominal interest rate receives repayment with lower real purchasing power than expected, thus losing.
- A pensioner with a fixed pension suffers a loss in real purchasing power.
- An employee whose salary is adjusted to actual inflation is protected but does not gain from the unexpected inflation.

Award 1 mark for the correct answer B. No marks for other options.

Initially, required reserves = \$1,000M \times 20\% = \$200M. Actual reserves = \$300M, so initial excess reserves = \$100M.
When the public deposits \$100M cash:
- Cash in circulation decreases by \$100M ($\Delta C = -\$100M$).
- Bank reserves increase by \$100M, making total reserves = \$300M + \$100M = \$400M.
Since banks hold no excess reserves in the end, the maximum deposits supported by \$400M of reserves is:
Final Deposits = \$400M / 0.2 = \$2,000M.
Change in deposits ($\Delta D$) = \$2,000M - \$1,000M = +\$1,000M.
Thus, the maximum change in money supply ($\Delta M_s = \Delta C + \Delta D$) is:
$-\$100M + \$1,000M = +\$900M$.

Award 1 mark for the correct answer C. No marks for other options.

- Reducing the personal income tax rate increases disposable income, leading to higher consumption and investment, which shifts Aggregate Demand (AD) to the right. This causes the price level and real GDP to rise.
- A rise in imported raw material prices increases production costs, shifting Short-run Aggregate Supply (SRAS) to the left. This causes the price level to rise and real GDP to fall.
Combining both effects, the general price level will definitely rise, while the effect on real GDP is uncertain.

Award 1 mark for the correct answer B. No marks for other options.

An import tariff increases the domestic price of the imported good:
- Domestic price rises, causing domestic consumption (quantity demanded) to decrease (A is incorrect).
- Domestic production (quantity supplied) increases (B is incorrect).
- Consumer surplus decreases due to the higher price and lower consumption, while domestic producer surplus increases due to the higher price (C is correct).
- Government revenue increases because of the tariff collected (D is incorrect).

Award 1 mark for the correct answer C. No marks for other options.

Initially, the net benefits of the three options are: Option 1: $150; Option 2: \(210 - 80 = 130\); Option 3: $110. The student chooses Option 1 (Study). The opportunity cost of studying is the net benefit of Option 2, which is $130. After the ticket price decreases to $70, the net benefit of Option 2 becomes \(210 - 70 = 140\). Since \(150 > 140\), the student still chooses to study. The opportunity cost of studying increases to $140.

B is the correct option. 1 mark for the correct answer.

Since Good A and Good B are close substitutes, the demand for Good A is price-elastic (\(E_d > 1\)). When the price of Good A increases, the percentage decrease in quantity demanded of A is larger than the percentage increase in price, leading to a decrease in its total revenue. Furthermore, since they are substitutes, an increase in the price of Good A will cause consumers to buy more of Good B, shifting the demand curve for Good B to the right (increase in demand).

C is the correct option. 1 mark for the correct answer.

An effective price ceiling is set below the equilibrium price, resulting in a shortage where quantity demanded exceeds quantity supplied. When demand increases (the demand curve shifts to the right), the quantity demanded at the ceiling price increases, while the quantity supplied remains unchanged at the fixed ceiling price. Therefore, the shortage of rental housing increases.

B is the correct option. 1 mark for the correct answer.

The marginal products (MP) are: 1st worker = 10; 2nd worker = 14; 3rd worker = 12; 4th worker = 10; 5th worker = 6; 6th worker = 3. Since MP increases from 10 to 14 and then falls to 12 with the 3rd worker, the Law of Diminishing Marginal Returns sets in when the 3rd worker is hired. Average products (AP) are: 10, 12, 12, 11.5, 10.4, 9.17, which is maximized at 2 and 3 workers, not 4.

B is the correct option. 1 mark for the correct answer.

When the customer withdraws $50 million of cash, bank reserves decrease by $50 million. The maximum decrease in deposits is \(50 / 0.20 = 250\) million. Since the cash in public circulation increases by $50 million, the net change in the money supply is: change in deposits (\(-250\) million) + change in cash (\(+50\) million) = \(-200\) million. Thus, the money supply decreases by $200 million.

B is the correct option. 1 mark for the correct answer.

Let's calculate opportunity costs. For Country X: 1 Computer = 2 Wine (1 Wine = 0.5 Computer). For Country Y: 1 Computer = 4 Wine (1 Wine = 0.25 Computer). Thus, Country X has a comparative advantage in producing computers, and Country Y has a comparative advantage in producing wine. The terms of trade for 1 Computer must lie between 2 Wine and 4 Wine for mutually beneficial trade. Since 3 Wine lies in this range, both countries gain. Country Y has the absolute advantage in both goods because it requires fewer hours (8 < 10 and 2 < 5).

C is the correct option. 1 mark for the correct answer.

Unanticipated inflation reduces the purchasing power of money. For a tenant with a fixed monthly rental payment, the real value of the rent paid decreases. Hence, the tenant benefits at the expense of the landlord. Debtors/tenants benefit while creditors/landlords lose. Workers with backward-looking adjustments and retired people with fixed pensions will lose real purchasing power.

C is the correct option. 1 mark for the correct answer.

Increasing government spending (\(G \uparrow\)) and reducing taxes (\(T \downarrow\)) are expansionary fiscal policies. These policies directly and indirectly increase Aggregate Demand (\(AD\)). At the same time, because government spending rises while tax revenues fall, the government's budget balance will deteriorate, meaning the budget deficit will increase (or budget surplus will decrease).

A is the correct option. 1 mark for the correct answer.

An increase in the import tariff on raw materials increases production costs, shifting the Short-Run Aggregate Supply (SRAS) curve to the left, which increases the price level and decreases real output. A reduction in the personal income tax rate increases disposable income, leading to an increase in private consumption and shifting the Aggregate Demand (AD) curve to the right, which increases both the price level and real output. Thus, the price level definitely increases, while the effect on real output is uncertain.

B is the correct option. 1 mark for the correct answer.

(1) is included because GDP measures the value of production within the domestic boundary. Since the catering service is produced in Hong Kong, the Japanese chef's labor income is part of HK's GDP. (2) is excluded because second-hand goods do not involve current production (the value of the smartphone was already counted in the year of production). (3) is excluded because government cash payouts are transfer payments, which do not involve any current production of goods or services.

A is the correct option. 1 mark for the correct answer.

Let us calculate the opportunity cost of producing \(1\) Smartphone:
- Country A: \(\frac{200}{100} = 2\) T-shirts
- Country B: \(\frac{240}{60} = 4\) T-shirts

Since Country A has a lower opportunity cost in producing Smartphones (\(2\text{ T-shirts} < 4\text{ T-shirts}\)), Country A has a comparative advantage in producing Smartphones, while Country B has a comparative advantage in producing T-shirts.

Since Country B has a comparative advantage in T-shirts, it will specialize in and export T-shirts, and import Smartphones.

If the mutually beneficial exchange ratio is \(1\text{ Smartphone} = 3\text{ T-shirts}\), which lies between the two countries' opportunity costs (\(2\text{ T-shirts} < 3\text{ T-shirts} < 4\text{ T-shirts}\)), both countries can benefit from trade. Country B will import Smartphones, which is correct.

Option A is incorrect because Country B has a comparative advantage in T-shirts.
Option B is incorrect because the opportunity cost of \(1\) Smartphone in Country B is \(4\) T-shirts.
Option D is incorrect because Country B has an absolute advantage in producing T-shirts (\(240 > 200\)).

Award 1 mark for the correct option C. No marks are awarded for incorrect options.

To close a recessionary gap, expansionary policies are required to increase aggregate demand (AD).
- Decreasing the income tax rate is an expansionary fiscal policy, which increases household disposable income and consumption, shifting the AD curve to the right.
- Decreasing the discount rate is an expansionary monetary policy, which lowers borrowing costs for commercial banks, encouraging lending and investment, shifting the AD curve to the right.

The other options contain at least one contractionary policy which would reduce AD.

Award 1 mark for the correct option A. No marks are awarded for incorrect options.

Let us calculate the percentage changes:
- Percentage change in price: \(\%\Delta P = \frac{16 - 20}{20} \times 100\% = -20\%\)
- Percentage change in quantity demanded: \(\%\Delta Q_d = \frac{130 - 100}{100} \times 100\% = 30\%\)

Since the percentage change in quantity demanded (\(30\%\)) is greater than the percentage change in price (\(20\%\)), the demand for the good is price elastic. When demand is elastic, a fall in price leads to an increase in total revenue.
- Original total revenue: \(\$20 \times 100 = \$2,000\)
- New total revenue: \(\$16 \times 130 = \$2,080\)

Thus, total revenue increases because the percentage change in quantity demanded is greater than the percentage change in price. This corresponds to option B.

Award 1 mark for the correct option B. No marks are awarded for incorrect options.

When actual inflation (\(5\%\)) is higher than expected inflation (\(2\%\)), unexpected inflation occurs:
- Borrowers with fixed nominal interest rate loans benefit because they repay their debt with money that has less purchasing power than expected. The real interest rate they pay decreases (from expected \(4\% - 2\% = 2\%\) to actual \(4\% - 5\% = -1\%\)). This corresponds to option C.
- Fixed-pension retirees (Option A) and landlords with fixed rents (Option B) lose purchasing power because their fixed nominal income buys fewer goods and services than expected.
- Fixed-rate savers (Option D) lose because the real return on their deposit is lower than expected (\(3\% - 5\% = -2\%\) instead of \(3\% - 2\% = 1\%\)).

Award 1 mark for the correct option C. No marks are awarded for incorrect options.

Let us calculate the marginal product (MP) of each unit of labour:
- 1st unit of labour: \(MP = 12 - 0 = 12\) units
- 2nd unit of labour: \(MP = 26 - 12 = 14\) units
- 3rd unit of labour: \(MP = 42 - 26 = 16\) units
- 4th unit of labour: \(MP = 56 - 42 = 14\) units
- 5th unit of labour: \(MP = 66 - 56 = 10\) units

The marginal product increases up to the 3rd unit of labour (reaching \(16\) units) and starts to decline at the 4th unit of labour (dropping to \(14\) units). Thus, the law of diminishing marginal returns begins to set in at the 4th unit of labour.

Award 1 mark for the correct option C. No marks are awarded for incorrect options.

Opportunity cost is the total value of the highest-valued alternative option forgone when making a decision.
By choosing to open the coffee shop, Kelvin has to forgo:
1. His current salary as an accountant: \(\$30,000\) per month (implicit cost / forgone income).
2. The operating cost of running the coffee shop: \(\$60,000\) per month (explicit cost / financial cost).

Therefore, the total opportunity cost of opening the coffee shop is:
\(\text{Opportunity Cost} = \$30,000 + \$60,000 = \$90,000\) per month.

Award 1 mark for the correct option C. No marks are awarded for incorrect options.

A price floor is the minimum price allowed by law.
- If a price floor is set below the equilibrium price, the market price can naturally remain at the higher equilibrium level because the floor does not prevent the price from rising or staying above it.
- Therefore, the price floor is non-binding (ineffective), and the market price and quantity transacted will remain unchanged at the equilibrium levels. Option C is correct.

Award 1 mark for the correct option C. No marks are awarded for incorrect options.

A technological breakthrough increases overall manufacturing productivity and reduces unit costs of production. This shifts the Short-run Aggregate Supply (SRAS) curve to the right.
- Under a constant Aggregate Demand (AD) curve, a rightward shift of the SRAS curve leads to a lower equilibrium price level and a higher level of equilibrium real GDP.
- Therefore, option B is correct.

Award 1 mark for the correct option B. No marks are awarded for incorrect options.

Money Supply (\(M\)) = Cash held by the public (\(C_p\)) + Deposits (\(D\)).
1. When the customer withdraws \(\$5,000\) cash, \(C_p\) increases by \(\$5,000\) (\(\Delta C_p = +\$5,000\)).
2. The reserves in the banking system decrease by \(\$5,000\).
3. Given a required reserve ratio of \(10\%\), the maximum deposit contraction is:
\(\Delta D = \Delta \text{Reserves} \times \frac{1}{\text{Required Reserve Ratio}} = -\$5,000 \times \frac{1}{0.10} = -\$50,000\).
4. The maximum change in the money supply is:
\(\Delta M = \Delta C_p + \Delta D = +\$5,000 + (-\$50,000) = -\$45,000\).

Thus, the money supply decreases by a maximum of \(\$45,000\) (Option B).

Award 1 mark for the correct option B. No marks are awarded for incorrect options.

Let us analyze the options:
- Option A: The commission earned by the real estate agent represents payment for productive services provided in Hong Kong in the current year. Thus, it is included in Hong Kong's GDP.
- Option B: The sale of a second-hand car is a transfer of ownership of a pre-existing asset. No new production takes place, so it is excluded.
- Option C: Government cash payouts are transfer payments and do not involve any production of goods or services, so they are excluded.
- Option D: The voluntary teaching services are unpaid (non-market transaction) and are provided in Mainland China (outside Hong Kong's economic territory), so they are excluded.

Award 1 mark for the correct option A. No marks are awarded for incorrect options.

The opportunity cost of choosing Project A is the value of the highest-valued option forgone, which is Project B.
- (1) If the construction cost of Project B decreases, the net value of Project B increases. Since Project B remains the second-best option (or becomes the best option), the value of the forgone alternative increases. Thus, the opportunity cost of choosing Project A increases.
- (2) Since Project C remains less valuable than Project B, Project B is still the highest-valued forgone option. The opportunity cost of Project A remains unchanged.
- (3) A tax on Project A decreases the net value of Project A, but does not affect the value of Project B. If Project A is still chosen, its opportunity cost is unchanged.
- (4) If the expected revenue of Project B increases but is still lower than Project A, Project B remains the second-best option and its net value increases. Thus, the opportunity cost of choosing Project A increases.

Award 1 mark for the correct option B. Reject all other options.

- Since Good X is an inferior good, an increase in consumers' income will decrease its demand. Since the demand is perfectly inelastic, the vertical demand curve shifts to the left, which leads to a decrease in the equilibrium quantity.
- The per-unit tax on sellers shifts the supply curve vertically upwards.
- The leftward shift of the demand curve exerts a downward pressure on price, while the upward shift of the supply curve exerts an upward pressure on price. Therefore, the net effect on the equilibrium price is uncertain.

Award 1 mark for the correct option C. Reject all other options.

First, calculate the Marginal Product (MP) and Average Product (AP) for each unit of labor:
- For 1 unit: $MP = 15$, $AP = 15$
- For 2 units: $MP = 32 - 15 = 17$, $AP = 32 / 2 = 16$
- For 3 units: $MP = 45 - 32 = 13$, $AP = 45 / 3 = 15$
- For 4 units: $MP = 56 - 45 = 11$, $AP = 56 / 4 = 14$
- For 5 units: $MP = 65 - 56 = 9$, $AP = 65 / 5 = 13$

Now evaluate the statements:
- (1) MP increases from 15 to 17, and then decreases to 13. Therefore, MP begins to decrease when the 3rd unit of labor is employed. Statement (1) is correct.
- (2) AP is 15, 16, 15, 14, 13 respectively. The maximum AP is 16 when the 2nd unit is employed. Statement (2) is correct.
- (3) The MP of the 4th unit of labor is $56 - 45 = 11$ units. Statement (3) is correct.

Award 1 mark for the correct option D. Reject all other options.

- When the public withdraws $50 cash, actual reserves in the banking system decrease by $50 (from $300 to $250), and cash in public hands increases by $50.
- Since the required reserve ratio is 20% and there are no excess reserves in the end, the maximum deposits the banking system can support is: $250 / 0.20 = $1250.
- The change in deposits is: $1250 - $1500 = -$250.
- The change in the money supply is: Change in cash in public hands + Change in deposits = +$50 + (-$250) = -$200 (i.e., a decrease of $200).

Award 1 mark for the correct option B. Reject all other options.

- Let's calculate the opportunity cost of producing 1 unit of Good X:
- In Country A: $4 / 2 = 2$ units of Good Y.
- In Country B: $3 / 3 = 1$ unit of Good Y.
- Since Country B has a lower opportunity cost in producing Good X ($1 < 2$), Country B has a comparative advantage in producing Good X. It will specialize in and export Good X.
- Correspondingly, Country A has a comparative advantage in producing Good Y and will export Good Y.
- Under the terms of trade ($1 \text{ X} = 1.5 \text{ Y}$), Country B exports $1 \text{ X}$ and receives $1.5 \text{ Y}$. Since Country B's domestic cost of producing $1 \text{ X}$ is $1 \text{ Y}$, Country B's gain per unit of Good X exported is: $1.5 \text{ Y} - 1 \text{ Y} = 0.5$ units of Good Y.

Award 1 mark for the correct option B. Reject all other options.

(a) The import quota reduces the total supply of wheat in the domestic market, creating a shortage at the world price \(P_w\). As a result, the domestic price of wheat will rise above \(P_w\). (b) Since the domestic price increases and the quantity consumed decreases, the consumer surplus of domestic consumers will decrease.

(a) Quota reduces domestic supply, causing shortage at \(P_w\) and thus domestic price rises [2 marks]. (b) Higher domestic price and lower quantity consumed lead to a decrease in consumer surplus [2 marks].

An increase in the required reserve ratio reduces the banking system's ability to create credit (or reduces the money multiplier), leading to a contraction in the money supply. As the money supply curve shifts to the left, with money demand remaining unchanged, the nominal interest rate will rise.

Explain the decrease in money supply due to reduced credit creation capability [2 marks]. Explain that the decrease in money supply shifts the supply curve left, raising the nominal interest rate [2 marks].

The law of demand states that, other things being constant, when the price of a good increases, its quantity demanded decreases, and vice versa. Since a decrease in price leads to an increase in total revenue, the percentage increase in quantity demanded must be greater than the percentage decrease in price. Therefore, the price elasticity of demand for cinema tickets is elastic.

State the law of demand [1 mark]. Correctly identify that the demand is elastic [1 mark]. Explain that the percentage increase in quantity demanded is greater than the percentage decrease in price, leading to an increase in total revenue [2 marks].

The fixed-rate mortgage borrower gains while the lending bank loses. When the actual inflation rate (\(5\%\)) is higher than the expected inflation rate (\(2\%\)), the real value of the fixed mortgage repayments decreases. This means the borrower repays the loan with money that has lower purchasing power than originally expected. Thus, the borrower gains. On the other hand, the lending bank receives repayments with lower purchasing power than expected, resulting in a loss.

Identify that the borrower gains and the bank loses [2 marks]. Explain that actual inflation higher than expected inflation reduces the real value of repayments / purchasing power of repayments, benefiting the debtor at the expense of the creditor [2 marks].

The Law of Diminishing Marginal Returns states that as more units of a variable factor are added continuously to a given quantity of fixed factors, the marginal product of the variable factor will eventually decrease, other things being constant. This law applies only to the short run because by definition, there is at least one fixed factor of production in the short run. In the long run, all factors of production are variable, so there are no fixed factors to which variable factors can be added.

Define the law: variable factor added to fixed factor (1 mark), marginal product eventually decreases (1 mark). Explain that the short run has fixed factors while in the long run all factors are variable (2 marks).

Opportunity cost is the highest-valued option forgone. Since the \(\$500\) ticket is non-refundable, it is a sunk cost and does not affect the decision. Initially, the opportunity cost of attending the concert was staying at home to study (valued at \(\$300\)). With the new part-time job offer, the alternative options are studying (\(\$300\)) and working (\(\$400\)). The highest-valued option forgone becomes working (\(\$400\)). Therefore, the opportunity cost of attending the concert increases from \(\$300\) to \(\$400\).

Define opportunity cost [1 mark]. Explain that the \(\$500\) ticket is a sunk cost and should be ignored [1 mark]. State that the original opportunity cost was \(\$300\) [1 mark]. State that the new opportunity cost is \(\$400\) (highest alternative forgone) and has therefore increased [1 mark].

(a) Since the price floor is set above the equilibrium rent, the quantity supplied of rental housing will exceed the quantity demanded, resulting in a surplus. The quantity transacted will decrease from the equilibrium quantity to the quantity demanded at the price floor. (b) Because of the surplus, some landlords cannot find tenants at the official price floor. To avoid vacancy, they may secretly offer rental housing at a price below the price floor, leading to the emergence of a black market.

(a) Explain that price floor above equilibrium causes a surplus, reducing the transacted quantity to the level of demand [2 marks]. (b) Explain that the surplus motivates landlords to secretly lower rents below the floor, creating a black market [2 marks].

A technological breakthrough increases the productivity of resources, which shifts the short-run aggregate supply (SRAS) curve to the right. Assuming aggregate demand (AD) remains unchanged, the rightward shift of the SRAS curve leads to an excess supply of goods and services at the original price level. As a result, the price level of the country will decrease, and the real output will increase in the short run.

State that the technological breakthrough shifts the SRAS curve to the right [1 mark]. Explain that this creates excess supply at the original price level, leading to a downward adjustment of prices [1 mark]. Conclude that price level decreases [1 mark] and real output increases [1 mark].

The withdrawal of \(\$100\) million reduces cash reserves in the banking system by \(\$100\) million. The banking multiplier is: \(\text{Multiplier} = 1 / \text{Required Reserve Ratio} = 1 / 20\% = 5\). The maximum contraction in deposits is: \(\Delta D = \Delta \text{Reserves} \times \text{Multiplier} = -\$100\text{ million} \times 5 = -\$500\text{ million}\). Since the \(\$100\) million is deposited in a foreign bank, it leaves the domestic banking system, meaning there is no change in domestic cash in circulation (\(\Delta C_p = 0\)). Thus, the maximum change in the domestic money supply is: \(\Delta M = \Delta C_p + \Delta D = 0 + (-\$500\text{ million}) = -\$500\text{ million}\) (i.e., a decrease of \(\$500\) million).

Identify the banking multiplier as 5 [1 mark]. Calculate the maximum change in deposits as \(-\$500\) million [2 marks]. State or show that cash in circulation is unchanged, concluding that the maximum decrease in money supply is \(\$500\) million [1 mark].

Part (a):
- When a per-unit subsidy is introduced, production cost decreases, shifting the supply curve downward parallelly by \$10.
- Equilibrium price paid by consumers falls, and equilibrium quantity increases, leading to an increase in consumer surplus.
- Effective price received by producers rises, and equilibrium quantity increases, leading to an increase in producer surplus.

Part (b):
(i) Producers will receive a larger share of the subsidy benefit. Since demand is more price-elastic than supply, consumers are highly sensitive to price changes. Thus, the decrease in the consumer-paid price is smaller than the increase in the producer-received price.
(ii) In the diagram, the demand curve is drawn relatively flat (elastic) and the supply curve relatively steep (inelastic). The shift in supply shows that the producer benefit share \((P_s - P_0)\) is greater than the consumer benefit share \((P_0 - P_1)\).

Part (c):
- The claim is correct if either demand or supply is perfectly inelastic (elasticity = 0).
- If demand or supply is perfectly inelastic, the equilibrium quantity remains unchanged after the subsidy is introduced. No overproduction occurs, meaning there is no distortion in resource allocation, and deadweight loss is zero.

Part (a) [Max 6 marks]:
- Diagram (3 marks):
- Correct downward shift of the supply curve (S to S') [1 mark]
- Correctly marking the initial and new equilibrium price and quantity [1 mark]
- Correctly showing the areas representing the increase in consumer surplus and producer surplus [1 mark]
- Explanation (3 marks):
- Explain that subsidy lowers production cost, increasing supply. [1 mark]
- Explain why consumer surplus increases (lower price and higher quantity). [1 mark]
- Explain why producer surplus increases (higher net price and higher quantity). [1 mark]

Part (b)(i) [Max 3 marks]:
- State that producers get a larger share. [1 mark]
- Explain that more elastic demand means consumers are more price sensitive. [1 mark]
- Conclude that the price falls by less than the subsidy, leaving more benefit to the less elastic side (producers). [1 mark]

Part (b)(ii) [Max 4 marks]:
- Diagram (4 marks):
- Demand curve is drawn visibly flatter than supply curve. [1 mark]
- Supply curve shifts down parallelly. [1 mark]
- Clearly mark original price \(P_0\), new consumer price \(P_1\), and new producer price \(P_s\). [1 mark]
- Clearly show that producer benefit \((P_s - P_0) > (P_0 - P_1)\). [1 mark]

Part (c) [Max 3 marks]:
- State that demand or supply is perfectly inelastic. [1 mark]
- Explain that quantity does not change. [1 mark]
- Conclude that resource allocation is not distorted / no overproduction, so deadweight loss is zero. [1 mark]

Part (a):
(i)
- Opportunity cost of producing 1 unit of Food in Country A: \(10 / 5 = 2\) units of Robots.
- Opportunity cost of producing 1 unit of Food in Country B: \(6 / 4 = 1.5\) units of Robots.
(ii)
- Country B has a comparative advantage in producing Food.
- Because Country B's opportunity cost of producing Food (1.5 R) is lower than Country A's (2 R).

Part (b):
(i)
- For Country B (Exporter of Food): It exports 10 units of Food and imports \(10 \times 1.8 = 18\) units of Robots. If it produced 10 units of Food domestically, it would cost \(10 \times 1.5 = 15\) units of Robots. Thus, Country B gains \(18 - 15 = 3\) units of Robots.
- For Country A (Importer of Food): It imports 10 units of Food and pays 18 units of Robots. If it produced 10 units of Food domestically, it would cost \(10 \times 2 = 20\) units of Robots. Thus, Country A saves/gains \(20 - 18 = 2\) units of Robots.
(ii)
- The mutually beneficial range is: \(1.5 \text{ units of Robots} < 1 \text{ unit of Food} < 2 \text{ units of Robots}\).

Part (c):
- Diagram: Shows domestic demand (D) and supply (S). World price line is horizontal at \(P_w\), and the tariff shifts it up to \(P_w + t\). Imports shrink from \((Q_{d1} - Q_{s1})\) to \((Q_{d2} - Q_{s2})\). Deadweight loss is represented by the two triangles adjacent to the tariff revenue rectangle.
- Explanation:
- The tariff raises the domestic price of Food from \(P_w\) to \(P_w + t\).
- Due to the higher price, domestic quantity supplied increases while domestic quantity demanded decreases, causing imports to fall.
- A deadweight loss is created because of production distortion (higher-cost domestic production replaces lower-cost imports) and consumption distortion (consumers lose marginal benefit from under-consumption).

Part (a)(i) [Max 2 marks]:
- Correct calculation for Country A. [1 mark]
- Correct calculation for Country B. [1 mark]

Part (a)(ii) [Max 3 marks]:
- Identify Country B. [1 mark]
- Compare opportunity costs (1.5 R < 2 R). [2 marks]

Part (b)(i) [Max 4 marks]:
- Show calculation and gain for Country B (3 Robots). [2 marks]
- Show calculation and gain for Country A (2 Robots). [2 marks]

Part (b)(ii) [Max 2 marks]:
- Mention opportunity cost range limit of 1.5 R. [1 mark]
- Mention opportunity cost range limit of 2 R. [1 mark]

Part (c) [Max 5 marks]:
- Diagram (2 marks):
- Correctly drawing the tariff price line \(P_w + t\) above \(P_w\). [1 mark]
- Correctly indicating the import reduction and deadweight loss areas (two triangles). [1 mark]
- Explanation (3 marks):
- Explain how tariff increases the domestic price. [1 mark]
- Explain the reduction in import volume due to changes in domestic Qd and Qs. [1 mark]
- Explain the source of the deadweight loss (production distortion and consumption distortion). [1 mark]

Part (a)
(i) Opportunity cost of producing 1 unit of Food (\(F\)):
- For Country A: \(4/2 = 2\) units of Clothing (\(C\)).
- For Country B: \(6/5 = 1.2\) units of Clothing (\(C\)).
Since Country B has a lower opportunity cost in producing Food (\(1.2C < 2C\)), Country B has the comparative advantage in producing Food.

(ii) Diagram requirements:
- Axes correctly labeled: Price (\(P\)) and Quantity (\(Q\)).
- Downward-sloping domestic demand (\(D\)) and upward-sloping domestic supply (\(S\)) curves.
- World price line (\(P_w\)) and tariff-inclusive price line (\(P_t\)) drawn horizontally below the domestic equilibrium price.
- Correctly show domestic production increasing (from \(Q_1\) to \(Q_2\)) and imports decreasing (from \(Q_4 - Q_1\) to \(Q_3 - Q_2\)).
- Correctly shade the two deadweight loss triangles (production distortion on the left, consumption distortion on the right).

Part (b)
(i) AD-AS Diagram and explanation:
- Draw the LRAS curve vertically, with the initial equilibrium (intersection of AD and SRAS) located to the left of the LRAS curve (representing a recessionary gap).
- Show expansionary fiscal policy by shifting the AD curve to the right (from \(AD_0\) to \(AD_1\)).
- Show the new equilibrium at the full-employment output level (on the LRAS curve).
- Explanation: Government spending is a component of aggregate demand (\(AD = C + I + G + NX\)). An increase in \(G\) shifts the AD curve to the right, which increases real GDP, closes the recessionary gap, and increases the general price level.

(ii) Under a fixed exchange rate system, the exchange rate is pegged. If Country A's central bank attempts to conduct an independent expansionary monetary policy (e.g., lowering interest rates), capital will flow out of the country seeking higher yields elsewhere. This puts depreciation pressure on the local currency. To maintain the peg, the central bank must buy its own currency and sell foreign reserves, which contracts the money supply and offsets the initial expansionary monetary policy. Thus, independent monetary policy is ineffective.

(iii) Disagree. An increase in government spending may lead to a 'crowding-out effect' where government borrowing to finance spending raises interest rates, reducing private consumption and investment, offsetting some of the AD increase. Alternatively, in the long run, when the economy is at full employment (vertical LRAS), any increase in government spending only leads to inflation without changing real GDP.

Part (c)
(i) Required reserves = \$1,000 million \times 20\% = \$200 million.
Excess reserves = Total reserves - Required reserves = \$250 million - \$200 million = \$50 million.

(ii) Under the new legal minimum reserve ratio of 15%:
- The current reserves of \$250 million can support a maximum deposits of: \$250 million / 15\% = \$1,666.67 million.
- Since original deposits are \$1,000 million, the maximum change in deposits (and thus money supply, as there is no cash leakage) is: \$1,666.67 million - \$1,000 million = \$666.67 million.

(iii) The 'Store of value' function is severely affected. Under hyperinflation, money loses its purchasing power rapidly, making it a poor asset to hold. Individuals will prefer holding real assets (e.g., gold, property) over money.
(Alternatively: The 'Medium of exchange' function is affected because people may refuse to accept money and resort to barter trade.)

Part (a)
(i)
- Opportunity cost of Country A: 2C [1M]
- Opportunity cost of Country B: 1.2C [1M]
- Conclusion with comparison: Country B has the comparative advantage [1A]

(ii)
- Correct axes, D and S curves [1M]
- World price and tariff price lines correctly drawn [1M]
- Correct indications of changes in domestic production and imports [1M]
- Correctly shaded deadweight loss areas [2M]

Part (b)
(i)
- Correct AD-AS diagram showing recessionary gap [2M]
- Shift AD curve to the right and show new equilibrium [2M]
- Explanation: Government spending increases AD, shifting the AD curve rightwards to restore full employment [2M]

(ii)
- Linking expansionary monetary policy with capital outflow and currency depreciation pressure [1M]
- Central bank intervention (buying local currency/selling reserves) to maintain the peg [1M]
- Conclusion: monetary base contracts, rendering independent policy ineffective [1M]

(iii)
- State 'Disagree' [1M]
- Explanation of crowding-out effect (higher interest rates reduce private spending) OR supply constraints in the long run (vertical LRAS) [2M]

Part (c)
(i)
- Required Reserves = $200 million [1M]
- Excess Reserves = $50 million [1M]

(ii)
- Max potential deposits with 15% reserve ratio = $1,666.67 million [1M]
- Correct method/formula for finding change in deposits [2M]
- Max increase in money supply = $666.67 million (accept $666.7 million) [1A]

(iii)
- Identify a correct function (e.g., store of value or medium of exchange) [1M]
- Elaborate how hyperinflation erodes the usefulness of this function [1M]