2023 HKDSE 經濟 模拟试题及答案详解

1. Opportunity cost is the highest-valued option forgone.
2. Originally, the $600 spent on the ticket is a sunk cost and irrelevant to future decisions. The best forgone alternative was earning $450 from tutoring, so the original opportunity cost was $450.
3. When the resale option is introduced, by attending the concert Kelvin forgoes the opportunity to receive $700 in cash. Since $700 > $450, the highest-valued forgone alternative becomes $700.
4. Therefore, his opportunity cost increases from $450 to $700.

B (1 mark)
- Option B is correct: The resale value of $700 exceeds the alternative earnings of $450 and represents the new highest-valued alternative forgone.

1. Opportunity costs:
- Country A: \(1\text{ toy} = 0.5\text{ watch}\) \(\iff 1\text{ watch} = 2\text{ toys}\).
- Country B: \(1\text{ toy} = 1\text{ watch}\) \(\iff 1\text{ watch} = 1\text{ toy}\).

2. Statement (1): Country A has a lower opportunity cost in producing toys (0.5 watch < 1 watch), so Country A has a comparative advantage in toys. Statement (1) is correct.

3. Statement (2): Mutually beneficial terms of trade for 1 watch lie between the opportunity costs of the two countries: \(1\text{ toy} < 1\text{ watch} < 2\text{ toys}\). Since 1.4 lies within this range, both countries gain from trade. Statement (2) is correct.

4. Statement (3): Total gain from trade per unit of watch traded without transportation cost is \(2 - 1 = 1\text{ toy}\). Since the transportation cost (\(0.4\text{ toys}\)) is less than the total gain (\(1\text{ toy}\)), there is still a net gain of \(0.6\text{ toys}\) to be shared between both countries. Mutually beneficial trade remains possible. Statement (3) is correct.

D (1 mark)
- Option D is correct: All three statements (1), (2), and (3) are logically sound based on the principle of comparative advantage and gains from trade.

1. A per-unit subsidy to producers shifts the supply curve rightward/downward.
2. This leads to a decrease in the market price paid by consumers (\(P\)) and an increase in the quantity transacted (\(Q\)).
3. Since demand is price inelastic (\(|E_d| < 1\)), the percentage decrease in price is greater than the percentage increase in quantity demanded.
4. As a result, total expenditure of consumers (\(TE = P \times Q\)), which also equals total revenue of sellers excluding subsidy, will decrease.
5. The consumer price falls by less than the subsidy because supply is not perfectly inelastic and demand is not perfectly elastic.

A (1 mark)
- Option A is correct: When price falls along an inelastic demand curve, total expenditure decreases.

1. Initial money supply \(M_1 = \text{Cash held by public} + \text{Deposits} = \$200\text{ million} + \$1,000\text{ million} = \$1,200\text{ million}\).
2. Maximum potential deposits supported by the current banking reserves ($300 million) at a 20% required reserve ratio:
$$\text{Maximum Deposits} = \frac{\text{Reserves}}{r_r} = \frac{\$300\text{ million}}{0.20} = \$1,500\text{ million}$$
3. Maximum potential money supply \(M_2 = \text{Cash held by public} + \text{Maximum Deposits} = \$200\text{ million} + \$1,500\text{ million} = \$1,700\text{ million}\).
4. Maximum possible increase in the money supply:
$$\Delta M = \$1,700\text{ million} - \$1,200\text{ million} = \$500\text{ million}$$

C (1 mark)
- Option C is correct: Maximum increase in money supply equals the change in deposits, which is $1,500 million - $1,000 million = $500 million.

1. Increase in the corporate profit tax rate lowers the expected after-tax return on investment, reducing investment expenditure (\(I\)). This causes the aggregate demand curve to shift to the left (\(AD \downarrow\)).
2. The surge in imported raw material prices increases unit production costs, causing the short-run aggregate supply curve to shift to the left (\(SRAS \downarrow\)).
3. Effects on output: Both \(AD \downarrow\) and \(SRAS \downarrow\) reduce aggregate output (\(Y\)), so aggregate output will definitely decrease.
4. Effects on price level: \(AD \downarrow\) exerts downward pressure on the price level, whereas \(SRAS \downarrow\) exerts upward pressure on the price level. The net change in the price level is therefore indeterminate without knowing the relative magnitude of the shifts.

A (1 mark)
- Option A is correct: Leftward shifts in both AD and SRAS unambiguously lower output and have opposite effects on the price level.

Statement (1) is correct: Country A can produce 4 units of clothing per unit of resource, which is greater than Country B's 3 units. Thus, Country A has an absolute advantage in clothing.

Statement (2) is correct: In Country B, 1 unit of resource produces 3 units of clothing OR 3 units of smart devices. Thus, the opportunity cost of producing 1 smart device = 3 / 3 = 1 unit of clothing.

Statement (3) is correct: In Country A, the opportunity cost of 1 smart device is 2 units of clothing (4 / 2). In Country B, it is 1 unit of clothing. Mutually beneficial terms of trade for 1 smart device lie strictly between 1 clothing and 2 clothing. At 1.5 clothing per smart device, Country B (the exporter of smart devices) receives more than its domestic cost (1.5 > 1), and Country A (the importer) pays less than its domestic cost (1.5 < 2). Both gain from trade.

D (1 mark)
[Award 1 mark for the correct option. No partial marks.]

Opportunity cost includes the highest-valued forgone alternative (implicit cost) plus all explicit costs incurred solely as a result of the choice.

1. Net forgone income = Income from full-time job - Income earned during studies = ($30,000 \times 12) - ($5,000 \times 12) = $360,000 - $60,000 = $300,000.
2. Direct explicit costs of studying = Tuition fee ($120,000) + Textbooks ($10,000) = $130,000.
3. The apartment rent ($8,000 per month) is incurred under both options and is therefore not an opportunity cost of choosing to study.

Total opportunity cost = $300,000 + $130,000 = $430,000.

A (1 mark)
[Award 1 mark for the correct option. No partial marks.]

A per-unit subsidy shifts the supply curve downwards/rightwards by $500. As a result, the equilibrium price paid by buyers (\(P_d\)) decreases and the equilibrium quantity (\(Q\)) increases.
- Because demand is elastic (\(|E_d| > 1\)), the percentage increase in quantity demanded is greater than the percentage decrease in price, so total consumer expenditure (\(P_d \times Q\)) increases (Option C is incorrect).
- The price received by sellers per unit becomes \(P_s = P_d + 500\), which increases, and the quantity sold \(Q\) increases. Therefore, total revenue received by producers inclusive of the subsidy (\(P_s \times Q\)) must increase (Option B is correct).
- The price paid by consumers falls by less than the $500 subsidy unless supply is perfectly inelastic (Option A is incorrect).
- Producer surplus increases due to higher net price and higher sales volume (Option D is incorrect).

B (1 mark)
[Award 1 mark for the correct option. No partial marks.]

According to the Fisher equation:
- Expected real interest rate = Nominal interest rate - Expected inflation rate = 5% - 2% = 3%.
- Actual real interest rate = Nominal interest rate - Actual inflation rate = 5% - 4% = 1%.

Since the actual inflation rate is higher than expected (unexpected inflation), the actual real interest rate is lower than expected (1% < 3%). Borrowers repay their loans in money with lower real purchasing power than anticipated, meaning borrowers gain at the expense of lenders (creditors).

C (1 mark)
[Award 1 mark for the correct option. No partial marks.]

1. Initially:
- Reserves = $400 million, Deposits = $2,000 million.
- Required reserves = 20% \times $2,000 million = $400 million (no initial excess reserves).
2. When the central bank buys $50 million of bonds from the public and the entire amount is deposited into banks:
- Total reserves become $400 million + $50 million = $450 million.
3. Maximum total deposits after full credit expansion:
- New Deposits = Total Reserves / Required Reserve Ratio = $450 million / 0.2 = $2,250 million.
- Change in money supply (which equals total deposits since cash holding is zero) = $2,250 million - $2,000 million = +$250 million.
4. New total bank loans:
- New Loans = New Deposits - New Reserves = $2,250 million - $450 million = $1,800 million.
- Change in bank loans = $1,800 million - $1,600 million = +$200 million.

A (1 mark)
[Award 1 mark for the correct option. No partial marks.]

Opportunity cost of an option is the value of the highest-valued alternative forgone plus any explicit/money cost incurred.

Initially:
- Explicit money cost of attending the art exhibition = $50.
- The alternatives forgone are Activity X (worth $200) and Activity Z (worth $180). The highest-valued alternative is Activity X ($200).
- Opportunity cost of attending the exhibition = $50 (money cost) + $200 (forgone tutoring income) = $250.

Evaluating the statements:
(1) If tutoring wage increases to $250, the value of the best alternative forgone rises from $200 to $250. The opportunity cost increases to $300. Thus, (1) changes the opportunity cost.
(2) If the valuation of badminton rises to $190, Activity X ($200) is still the highest-valued alternative forgone. The value of the best alternative remains $200. Thus, (2) does not change the opportunity cost.
(3) If admission becomes free, the explicit money cost drops from $50 to $0. The opportunity cost decreases from $250 to $200. Thus, (3) changes the opportunity cost.

Therefore, (1) and (3) only is the correct answer.

B (1 mark)
- (1) is correct: higher return from the best alternative forgone increases opportunity cost.
- (2) is incorrect: badminton is not the best alternative, so a change in its valuation does not affect opportunity cost.
- (3) is correct: reduction in money cost directly reduces opportunity cost.

Total Revenue (\(TR = P \times Q\)):
- At \(P = \$6\), \(Q = 60\), so \(TR_1 = \$6 \times 60 = \$360\).
- At \(P = \$4\), \(Q = 80\), so \(TR_2 = \$4 \times 80 = \$320\).

When price decreases from $6 to $4, total revenue decreases from $360 to $320.
When price and total revenue move in the same direction, the percentage increase in quantity demanded is smaller than the percentage decrease in price (i.e., \(|E_d| < 1\)). Hence, demand is inelastic.

C (1 mark)
- Correctly identifies that \(TR\) falls from $360 to $320 when price falls.
- Since price reduction leads to a fall in total revenue, demand is inelastic.

Calculate the opportunity costs:
- Country A: Cost of 1 unit of Toys = \(20 / 10 = 2\) units of Clothing. Cost of 1 unit of Clothing = \(10 / 20 = 0.5\) units of Toys.
- Country B: Cost of 1 unit of Toys = \(45 / 15 = 3\) units of Clothing. Cost of 1 unit of Clothing = \(15 / 45 = 1/3\) units of Toys.

Evaluation:
(1) Country A has a lower opportunity cost in producing toys (\(2\text{C} < 3\text{C}\)), so Country A has a comparative advantage in toys. Statement (1) is correct.
(2) Mutually beneficial terms of trade for 1 Toy must lie strictly between the domestic opportunity costs: \(2\text{C} < 1\text{T} < 3\text{C}\). Since \(2.5\text{C}\) lies within this range, both countries gain. Statement (2) is correct.
(3) The total gain from trade per unit of toy traded without transport cost is \(3\text{C} - 2\text{C} = 1\text{C}\). Since the transportation cost is \(0.6\text{C} < 1\text{C}\), a net gain of \(0.4\text{C}\) remains to be shared between both countries, so mutually beneficial trade is still possible. Statement (3) is correct.

Thus, (1), (2) and (3) are all correct.

D (1 mark)
- (1) is correct: Country A's cost of 1 Toy is 2 Clothing vs Country B's 3 Clothing.
- (2) is correct: Terms of trade 2.5 Clothing lies between 2 and 3 Clothing.
- (3) is correct: Transport cost (0.6 Clothing) is less than the difference in opportunity costs (1.0 Clothing).

Initial situation:
- Total deposits = $1,200 million.
- Actual reserves = $300 million.
- Required reserves = $1,200 \text{ million} \times 20\% = $240 \text{ million}.
- Excess reserves = $300 - $240 = $60 \text{ million}.

When $60 million cash is withdrawn:
- Bank reserves fall to $300 - $60 = $240 \text{ million}.
- With $240 million reserves and a 20% required reserve ratio, the maximum deposits the banking system can support = $240 \text{ million} / 0.20 = $1,200 \text{ million}.
- Therefore, after full adjustment, maximum total deposits remain $1,200 million (change in deposits = $0).

Change in money supply (\(M = \text{Cash held by non-bank public} + \text{Deposits}\)):
- Cash held by the public increases by $60 million.
- Total deposits change by $0.
- Net change in money supply = +$60 \text{ million} + $0 = +$60 \text{ million}.

B (1 mark)
- Initial excess reserves = $60M.
- Cash withdrawal of $60M exhausts excess reserves exactly, leaving $240M required reserves which can still support $1,200M deposits (change in deposits is $0).
- Public cash holdings increase by $60M, so money supply increases by $60M.

Effects of the two events in the short run:
1. An increase in government expenditure on transportation infrastructure is an expansionary fiscal measure that increases aggregate demand (\(AD\) shifts right).
- This puts upward pressure on the price level (\(P \uparrow\)) and upward pressure on real output (\(Y \uparrow\)).
2. A surge in international crude oil prices raises production costs for firms across the economy, causing short-run aggregate supply to decrease (\(SRAS\) shifts left).
- This puts upward pressure on the price level (\(P \uparrow\)) and downward pressure on real output (\(Y \downarrow\)).

Combined short-run effect:
- Price level: Both shifts increase the price level \(\implies\) Price level will definitely increase.
- Real output: \(AD\) shifting right increases \(Y\), while \(SRAS\) shifting left decreases \(Y\) \(\implies\) The net change in real output depends on the relative magnitudes of the two shifts, so it is indeterminate.

B (1 mark)
- Rightward shift in AD increases both P and Y.
- Leftward shift in SRAS increases P and decreases Y.
- Overall: P increases unambiguously; Y is indeterminate.

Statement (1) is correct: With 1 unit of resources, Country X produces more clothing (20 > 15) and more electronics (10 > 5) than Country Y, so Country X has an absolute advantage in both goods.

Statement (2) is correct: In Country X, the opportunity cost of 1 unit of clothing = 10/20 = 0.5 units of electronics. In Country Y, the opportunity cost of 1 unit of clothing = 5/15 = 0.33 units of electronics. Since Country Y incurs a lower opportunity cost in producing clothing, it has a comparative advantage in clothing.

Statement (3) is correct: For 1 unit of electronics, Country X's cost is 2 units of clothing and Country Y's cost is 3 units of clothing. Any terms of trade between 2 units and 3 units of clothing per unit of electronics (such as 2.5 units of clothing) will allow both countries to gain from trade.

Therefore, (1), (2) and (3) are all correct.

D (1 mark)
- (1) correct: absolute advantage assessed from higher productivity per unit of resources.
- (2) correct: comparative advantage determined by lower opportunity cost of clothing in Country Y.
- (3) correct: mutually beneficial terms of trade lie strictly between the domestic opportunity cost ratios (2C < 1E < 3C).

Percentage change in price = \((480 - 400) / 400 \times 100\% = +20\%\).
Percentage change in quantity demanded = \(-10\%\).

Statement (1) is correct: Since \(|\%\Delta Q_d| (10\%) < |\%\Delta P| (20\%)\), the price elasticity of demand is inelastic (\(|E_d| = 0.5 < 1\)).

Statement (2) is correct: When demand is inelastic, an increase in price leads to an increase in total revenue (\(TR = P \times Q\)).

Statement (3) is correct: Total revenue from snacks and souvenirs = (Number of visitors) \(\times\) (Average expenditure per visitor). Since the number of visitors drops by 10% and the average spending per visitor is unchanged, the total revenue from snack and souvenir sales decreases by 10%.

Therefore, (1), (2) and (3) are all correct.

D (1 mark)
- (1) correct: elasticity calculated as %ΔQd / %ΔP = 10% / 20% = 0.5 < 1 (inelastic).
- (2) correct: with inelastic demand, price increase raises total revenue.
- (3) correct: fewer visitors with constant spending per head implies lower total secondary revenue.

The $800 paid for the concert ticket is a sunk cost because it has already been incurred and cannot be recovered or changed by any current decision. It should not be included in the opportunity cost of choosing to attend the concert.

Kelly now faces two alternative options for Saturday evening:
1. Private tutoring: gain $300.
2. Art exhibition: valued at $500.

Opportunity cost is the value of the highest-valued alternative forgone. The highest-valued alternative is attending the art exhibition, which is valued at $500.

Therefore, the opportunity cost of attending the concert is $500.

B (1 mark)
- Non-refundable ticket price ($800) is a sunk cost and excluded from opportunity cost.
- Opportunity cost equals the highest-valued option forgone among available alternatives: max($300, $500) = $500.

Initial situation:
- Total deposits = Reserves + Loans = $200 million + $800 million = $1,000 million.
- Since the public holds no cash, initial money supply = Total deposits = $1,000 million.
- Required reserves = 20% \(\times\) $1,000 million = $200 million (no excess reserves).

New situation:
- Total bank reserves remain $200 million.
- With the required reserve ratio raised to 25%, the maximum possible deposits = \(\text{Reserves} / \text{Required Reserve Ratio} = \$200\text{ million} / 0.25 = \$800\text{ million}\).
- Maximum possible money supply = $800 million.

Change in maximum money supply = \(\$800\text{ million} - \$1,000\text{ million} = -\$200\text{ million}\) (decreases by $200 million).

B (1 mark)
- Initial money supply = $200M + $800M = $1,000M.
- New maximum money supply = $200M / 0.25 = $800M.
- Net change = $800M - $1,000M = -$200M (decrease by $200 million).

Actual inflation (1%) is lower than expected inflation (4%).

(1) A borrower paying a fixed nominal interest rate pays a higher real interest rate than anticipated (\(\text{Real interest rate} = \text{Nominal rate} - \text{Actual inflation}\)). Hence, the borrower loses.

(2) A tenant paying a fixed nominal rent gives up money with higher purchasing power than anticipated. The real rent paid is higher than expected, so the tenant loses.

(3) A firm receiving a fixed nominal revenue from selling products receives income with higher purchasing power than anticipated because the general price level rose less than expected. Hence, the firm gains.

Therefore, only (3) gains.

B (1 mark)
- Lower-than-expected inflation hurts fixed-rate debtors/payers (1 and 2 lose).
- Fixed-price sellers receive real revenue higher than expected (3 gains).

To find the comparative advantage, we calculate the opportunity cost of producing 1 unit of Good A in terms of Good B for each country:
- In Country X: Producing 1 unit of Good A requires 4 units of labour, which could have produced \(4/8 = 0.5\) units of Good B. Thus, the opportunity cost of 1 unit of Good A is \(0.5\text{ units of Good B}\).
- In Country Y: Producing 1 unit of Good A requires 6 units of labour, which could have produced \(6/3 = 2\) units of Good B. Thus, the opportunity cost of 1 unit of Good A is \(2\text{ units of Good B}\).

Since Country X has a lower opportunity cost in producing Good A (\(0.5 < 2\)), Country X has a comparative advantage in Good A and will export Good A.
Country Y has a lower opportunity cost in producing Good B (\(0.5 < 2\)), so Country Y will export Good B.

With the terms of trade at \(1\text{ A} = 1\text{ B}\):
- Country X exports 1 unit of Good A (cost: 0.5 B) and gets 1 unit of Good B. Country X gains \(1 - 0.5 = 0.5\text{ units of Good B}\) per unit of Good A exported.
- Country Y exports 1 unit of Good B (cost: 0.5 A) and gets 1 unit of Good A. Country Y gains \(1 - 0.5 = 0.5\text{ units of Good A}\) per unit of Good B exported.

Therefore, both countries gain from trade.

Correct Answer: B (1 mark).
- Option A is incorrect because Country X exports Good A, not Good B.
- Option B is correct as both countries gain 0.5 units of the imported good per unit of export.
- Option C is incorrect as the terms of trade lie strictly within the domestic opportunity cost ratios \(0.5\text{ B} < 1\text{ B} < 2\text{ B}\), yielding mutually beneficial trade.
- Option D is incorrect because Country Y has an absolute advantage in Good B (requires only 3 units of labour vs 8 in Country X).

Total revenue \(TR = P \times Q\).
Given that price (\(P\)) increases by 25% and \(TR\) increases by 10%, quantity demanded (\(Q\)) must have fallen, but by a smaller percentage than the price rise (specifically, \(1.25 \times (1 + \%\Delta Q) = 1.10 \implies 1 + \%\Delta Q = 0.88\), so \(Q\) decreases by 12%).

- (1) is correct: When a rise in price leads to an increase in total revenue, demand is price inelastic (\(E_d < 1\)).
- (2) is correct: The percentage drop in quantity demanded is 12%, which is less than the 25% price increase.
- (3) is incorrect: The supply curve shifted to the left; the observed price and quantity changes occur along the demand curve, so this provides information about the elasticity of demand, not the price elasticity of supply.

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

Correct Answer: A (1 mark).
- (1) is correct: \(P \uparrow \implies TR \uparrow\) indicates inelastic demand (\(|E_d| < 1\)).
- (2) is correct: \(\%\Delta Q = -12\%\), which is smaller in magnitude than \(\%\Delta P = +25\%\).
- (3) is incorrect: A shift in supply traces out the demand curve; supply elasticity cannot be deduced.

Opportunity cost of attending the concert is the value of the highest-valued option forgone plus any additional costs incurred in choosing that option.
1. The highest-valued alternative forgone was initially the cafe shift paying $300. When the wage increases to $420, the value of the best alternative forgone rises by $120.
2. The non-money cost (disutility/discomfort of travelling in heavy rain) of attending the concert also increases.

Both components (the value of the forgone option and the direct non-pecuniary costs of attending) increase, so Calvin's opportunity cost of attending the concert definitely increases.

Correct Answer: C (1 mark).
- Opportunity cost consists of the value of the best alternative forgone plus any explicit/implicit costs associated with the chosen action.
- Higher alternative wage ($300 to $420) increases forgone value.
- Increased travel difficulty increases the cost of the chosen option.
- Thus, total opportunity cost increases.

When the central bank purchases $40 million of government bonds from the public, $40 million is injected into the public's hands, which is fully deposited into the banking system.
- Initial increase in bank deposits = $40 million.
- Initial increase in actual reserves = $40 million.

Through the multiple credit expansion process:
- The banking multiplier \(M = 1 / \text{required reserve ratio} = 1 / 0.20 = 5\).
- Maximum change in total deposits \(\Delta D = \Delta R \times (1 / r) = +\$40\text{ million} \times 5 = +\$200\text{ million}\).
- The new reserves remain in the banking system as required reserves to support the expanded deposits (\(20\% \times \$200\text{ million} = \$40\text{ million}\)). Thus, the change in actual bank reserves is \(+\$40\text{ million}\).

Correct Answer: D (1 mark).
- Change in actual reserves \(\Delta R = +\$40\text{ million}\).
- Maximum change in total deposits \(\Delta D = \Delta R / r = +\$40 / 0.2 = +\$200\text{ million}\).

When actual inflation (7%) is higher than expected inflation (3%), the real purchasing power of money decreases faster than anticipated. This redistributes wealth from creditors/fixed-income receivers to debtors/fixed-obligation payers:

- Option A: A retired civil servant receiving a fixed monthly pension suffers a loss because the real purchasing power of the fixed income declines faster than expected.
- Option B: A homeowner repaying a mortgage with a fixed nominal interest rate gains because the real value of the fixed debt repayments is less than anticipated (the real interest rate paid is lower than expected).
- Option C: A commercial bank holding fixed-rate government bonds loses because the real return from the bond coupon and principal is reduced.
- Option D: A landlord leasing out residential property under a multi-year fixed nominal rent agreement loses because the real purchasing power of the rental income received is eroded.

Correct Answer: B (1 mark).
- Unexpected inflation (actual > expected) benefits borrowers with fixed nominal repayments.
- Lenders and fixed-income earners lose.

To produce \(1\text{ unit of Smartphones}\):
- Country X's opportunity cost is \(20 / 10 = 2\text{ units of Toy cars}\).
- Country Y's opportunity cost is \(15 / 15 = 1\text{ unit of Toy cars}\).

Since Country Y has a lower opportunity cost in producing Smartphones, Country Y specializes in and exports Smartphones, while Country X specializes in and exports Toy cars.

Evaluation of statements:
- (1) Country X produces \(20\) Toy cars per unit of resources compared to \(15\) in Country Y, so Country X has an absolute advantage in Toy cars. (Correct)
- (2) Country Y's domestic cost of \(1\text{ unit of Smartphones}\) is \(1\text{ unit of Toy cars}\). Since it receives \(1.6\text{ units of Toy cars}\) per Smartphone exported, its gain per unit is \(1.6 - 1.0 = 0.6\text{ units of Toy cars}\). (Correct)
- (3) Country X's domestic cost of \(1\text{ unit of Smartphones}\) is \(2.0\text{ units of Toy cars}\). Importing it at \(1.6\text{ units of Toy cars}\) saves \(2.0 - 1.6 = 0.4\text{ units of Toy cars}\). (Correct)

D (1 mark)
[1 mark for selecting the option containing (1), (2), and (3).]

1. Price elasticity of demand (\(|E_d|\)) = \(\frac{\%\text{ change in quantity demanded}}{\%\text{ change in price}} = \frac{18\%}{15\%} = 1.2 > 1\). Thus, demand is elastic. Statement (1) is correct.
2. When demand is price elastic (\(|E_d| > 1\)), the percentage increase in quantity demanded is greater than the percentage decrease in price, so total revenue (\(P \times Q\)) increases. Statement (2) is correct.
3. Total expenditure of consumers equals total revenue of the producer. Since total revenue increases, total expenditure must also increase. Statement (3) is incorrect.

A (1 mark)
[1 mark for identifying statements (1) and (2) as correct and (3) as incorrect.]

1. Initial position:
- Initial reserves = \(\$300\text{ million}\)
- Initial deposits = \(\$1{,}000\text{ million}\)
- Initial loans = \(\$700\text{ million}\)

2. After the \(\$50\text{ million}\) cash deposit:
- New total reserves = \(\$300\text{ million} + \$50\text{ million} = \$350\text{ million}\)

3. With a legal reserve ratio of \(20\%\) (\(0.2\)) and no excess reserves:
- Maximum total deposits = \(\frac{\text{Total Reserves}}{\text{Reserve Ratio}} = \frac{\$350\text{ million}}{0.2} = \$1{,}750\text{ million}\)
- Maximum total loans = \(\text{Total Deposits} - \text{Total Reserves} = \$1{,}750\text{ million} - \$350\text{ million} = \$1{,}400\text{ million}\)

4. Maximum possible increase in loans = \(\$1{,}400\text{ million} - \$700\text{ million} = \$700\text{ million}\).

C (1 mark)
[1 mark for calculating the new maximum loan capacity and finding the net change of $700 million.]

- (1) An effective price ceiling is set below the market equilibrium price, causing the quantity demanded to exceed the quantity supplied (\(Q_d > Q_s\)), resulting in a market shortage (excess demand). (Correct)
- (2) Because price can no longer allocate the scarce quantity, non-price rationing mechanisms (such as queues, rationing coupons, or favoritism) will emerge. (Correct)
- (3) Since the market price drops to the ceiling level and the actual quantity transacted falls to \(Q_s\), the area representing producer surplus must decrease. (Correct)

D (1 mark)
[1 mark for recognizing all three consequences of an effective price ceiling.]

- (1) The homeowner (debtor) repays the loan in fixed nominal terms. With unexpected inflation, the real purchasing power of the repayment amounts falls, so the debtor gains at the expense of the lender. (Gains)
- (2) The tenant pays a fixed nominal rent over three years. As the general price level rises, the real value of the rent paid falls, so the tenant gains. (Gains)
- (3) The retiree receives a fixed nominal pension. With inflation, the real purchasing power of this fixed income decreases, so the retiree loses. (Loses)

Therefore, only (1) and (2) gain.

A (1 mark)
[1 mark for identifying that fixed-nominal payers gain and fixed-nominal receivers lose under unanticipated inflation.]

To determine comparative advantage, calculate the opportunity cost of producing 1 unit of each good:
- In Country X: 1 unit of resources produces 20 units of clothing or 10 units of wheat. Thus, the opportunity cost of 1 unit of wheat = \(20 / 10 = 2\) units of clothing (and 1 unit of clothing = 0.5 unit of wheat).
- In Country Y: 1 unit of resources produces 15 units of clothing or 5 units of wheat. Thus, the opportunity cost of 1 unit of wheat = \(15 / 5 = 3\) units of clothing (and 1 unit of clothing = \(1/3\) unit of wheat).

Evaluating the statements:
- (1) is incorrect: Country X produces 20 units of clothing per unit of resource while Country Y produces 15 units. Country X has an absolute advantage in clothing.
- (2) is correct: Country X has a lower opportunity cost in producing wheat (2 units of clothing < 3 units of clothing), so Country X has a comparative advantage in wheat.
- (3) is correct: The mutually beneficial terms of trade for 1 unit of wheat lie strictly between the opportunity costs of the two countries: \(2\text{ units of clothing} < 1\text{ unit of wheat} < 3\text{ units of clothing}\). At 1 unit of wheat = 2.5 units of clothing, both countries gain from trade.

Therefore, (2) and (3) only are correct.

D (1 mark)
- (1) is incorrect because Country X produces more clothing per unit of resource (20 > 15).
- (2) is correct because the opportunity cost of producing 1 unit of wheat in Country X (2C) is lower than in Country Y (3C).
- (3) is correct because the terms of trade (1W = 2.5C) fall within the range 2C < 1W < 3C.

The opportunity cost of an action is the value of the highest-valued option forgone.

Initially, Kelvin's highest-valued option forgone when watching a movie is studying at the public library (2nd preference).
- (1) A discount on popcorn increases the value/benefit of Kelvin's chosen option (watching a movie), but does not affect the value of the highest-valued alternative forgone. Hence, opportunity cost remains unchanged.
- (2) Installing study pods increases the value of the 2nd preference (studying at the library). Since studying remains the highest-valued option forgone, its increased value raises the opportunity cost of watching the movie.
- (3) If the new video game becomes more attractive than studying at the library, playing video games becomes his new 2nd preference (the highest-valued alternative forgone). This changes the forgone option and therefore changes the opportunity cost.

Thus, (2) and (3) only will change his opportunity cost.

D (1 mark)
- (1) affects the net gain/value of the chosen option, not the opportunity cost.
- (2) changes the value of the highest-valued alternative forgone.
- (3) changes the identity and value of the highest-valued alternative forgone.

When supply decreases (shifts to the left), the equilibrium price rises (\(P \uparrow\)) and the equilibrium quantity falls (\(Q \downarrow\)).

- Total revenue \(TR = P \times Q\). Since \(TR\) increases when price rises, the positive price effect outweighs the negative quantity effect. This implies that the percentage increase in price is greater than the percentage decrease in quantity (i.e., \(\%\Delta Q < \%\Delta P\)). Thus, statement (1) is correct.
- By definition, when \(\%\Delta Q / \%\Delta P < 1\), demand is price inelastic (\(E_d < 1\)). Thus, statement (2) is correct.
- With a downward-sloping demand curve, an increase in equilibrium price accompanied by a decrease in equilibrium quantity unambiguously reduces the consumer surplus (the area between the demand curve and the price line). Thus, statement (3) is correct.

Therefore, (1), (2) and (3) are all correct.

D (1 mark)
- (1) is correct because TR rises with price increase only when %ΔQ < %ΔP.
- (2) is correct as Ed = %ΔQ / %ΔP < 1.
- (3) is correct because higher price and lower quantity reduce the area of consumer surplus.

An effective import quota restricts the quantity of foreign electric vehicles that can be imported below the free trade level:
- The reduced supply of imported electric vehicles pushes up their domestic selling price.
- Since domestically produced electric vehicles and imported electric vehicles are substitutes in consumption, the higher price of imported vehicles increases the demand for domestically produced electric vehicles.
- The demand curve for domestic electric vehicles shifts rightwards, leading to an increase in both their equilibrium price and equilibrium output quantity.
- Consequently, the total revenue (\(P \times Q\)) of domestic producers of electric vehicles definitely increases.

Evaluation of distractors:
- Option A is incorrect: The domestic price of imported electric vehicles will increase, not decrease.
- Option C is incorrect: The deadweight loss increases due to the distortion of trade and underconsumption.
- Option D is incorrect: The total quantity of electric vehicles sold (domestic + imports) will decrease overall due to the higher market price.

B (1 mark)
- An effective import quota raises the price of imported vehicles, shifting demand for domestic substitutes rightward, raising both price and quantity for domestic producers, thereby increasing their total revenue.

Step 1: Calculate the new total reserves in the banking system.
$$\text{New total reserves} = \text{Initial reserves} + \text{New cash deposit} = \$250\text{ million} + \$50\text{ million} = \$300\text{ million}$$

Step 2: Calculate the maximum possible total deposits with the new required reserve ratio (\(rrr = 15\%\)).
$$\text{Maximum total deposits} = \frac{\text{Total reserves}}{rrr} = \frac{\$300\text{ million}}{0.15} = \$2\text{,}000\text{ million}$$

Step 3: Calculate the maximum possible increase in total deposits.
$$\text{Maximum increase in deposits} = \text{Maximum total deposits} - \text{Initial deposits} = \$2\text{,}000\text{ million} - \$1\text{,}000\text{ million} = \$1\text{,}000\text{ million}$$

Hence, the correct option is B.

B (1 mark)
- Correct calculation of new total reserves: $250M + $50M = $300M.
- Maximum potential deposits = $300M / 0.15 = $2,000M.
- Maximum increase in deposits = $2,000M - $1,000M = $1,000M.

Statement (1) is correct: The $200 registration fee has already been paid and cannot be refunded or recovered regardless of her choice; thus, it is a sunk cost and is irrelevant to her decision.

Statement (2) is correct: The opportunity cost of attending the workshop is the highest-valued alternative forgone, which is the income from working as a freelance assistant: \(2 \text{ hours} \times \$150/\text{hour} = \$300\).

Statement (3) is correct: When the freelance hourly wage rises to $180, the forgone income increases to \(2 \times \$180 = \$360\). Hence, her opportunity cost of attending the workshop increases.

Therefore, statements (1), (2), and (3) are all correct.

D (1 mark)
- (1), (2) and (3) are all correct based on the economic concepts of sunk cost and opportunity cost.

Statement (1) is incorrect: Under normal upward-sloping supply and downward-sloping demand curves, the supply curve shifts vertically upwards by the tax amount, causing the equilibrium price to increase by LESS than the per-unit tax.

Statement (2) is correct: Because demand is price inelastic (\(|E_d| < 1\)), the percentage increase in price is greater than the percentage decrease in quantity demanded. Consequently, total consumer expenditure (\(P \times Q\)) increases.

Statement (3) is correct: The net price received by sellers after tax (\(P_{\text{net}} = P - t\)) decreases, and the quantity sold \(Q\) also decreases. Thus, total revenue net of tax (\(P_{\text{net}} \times Q\)) must decrease.

Therefore, only (2) and (3) are correct.

C (1 mark)
- (2) and (3) are correct based on the total expenditure test for inelastic demand and producer tax incidence.

Calculate the Marginal Product (\(MP\)) and Average Product (\(AP\)) of labor:
- \(L = 1\): \(MP = 15\), \(AP = 15.0\)
- \(L = 2\): \(MP = 34 - 15 = 19\), \(AP = 17.0\)
- \(L = 3\): \(MP = 57 - 34 = 23\), \(AP = 19.0\)
- \(L = 4\): \(MP = 76 - 57 = 19\), \(AP = 19.0\)
- \(L = 5\): \(MP = 90 - 76 = 14\), \(AP = 18.0\)
- \(L = 6\): \(MP = 96 - 90 = 6\), \(AP = 16.0\)

Option A is correct: \(MP\) increases from 15 to 19 to 23, and then starts to diminish at the 4th unit of labor (falls from 23 to 19). Hence, the law of diminishing marginal returns sets in when the 4th unit of labor is employed.

Option B is incorrect: At \(L = 4\), \(AP = 19.0\), which remains unchanged relative to \(L = 3\) (it does not increase).

Option C is incorrect: For the 5th unit of labor, \(MP = 14 < AP = 18\).

Option D is incorrect: Total variable cost increases monotonically with the quantity of labor employed.

A (1 mark)
- Identifying the point where MP begins to decrease indicates when diminishing marginal returns set in.

Calculate the opportunity costs of production for both countries:

- In Country A:
- Opportunity cost of 1 unit of Clothing \(= \frac{4}{2} = 2\) units of Food.
- Opportunity cost of 1 unit of Food \(= \frac{2}{4} = 0.5\) units of Clothing.

- In Country B:
- Opportunity cost of 1 unit of Clothing \(= \frac{6}{6} = 1\) unit of Food.
- Opportunity cost of 1 unit of Food \(= \frac{6}{6} = 1\) unit of Clothing.

Comparative Advantage:
- Country B has a lower opportunity cost in producing Clothing (\(1\text{ Food} < 2\text{ Food}\)), so Country B has a comparative advantage in Clothing and will export Clothing.
- Country A has a lower opportunity cost in producing Food (\(0.5\text{ Clothing} < 1\text{ Clothing}\)), so Country A has a comparative advantage in Food and will export Food.

Terms of trade for mutual benefit:
- For 1 unit of Clothing, the terms of trade must lie between the two domestic opportunity costs: \(1\text{ unit of Food} < 1\text{ unit of Clothing} < 2\text{ units of Food}\).
- The proposed rate of \(1\text{ unit of clothing} = 1.5\text{ units of food}\) falls strictly within this range.

Hence, Option C is correct.

C (1 mark)
- Mutually beneficial terms of trade must fall strictly between the opportunity costs of the two trading partners (1 Food < 1 Clothing < 2 Food).

Initial situation:
- Legal reserve ratio \(r_1 = 20\%\)
- Total reserves \(= \$400\) million
- Initial deposits \(D_1 = \frac{\$400\text{ million}}{0.20} = \$2,000\) million

New situation:
- New legal reserve ratio \(r_2 = 25\%\)
- Since the public does not hold cash, total reserves in the banking system remain \(\$400\) million.
- New maximum possible deposits \(D_2 = \frac{\text{Total Reserves}}{r_2} = \frac{\$400\text{ million}}{0.25} = \$1,600\) million.

Change in deposits:
\(\Delta D = \$1,600\text{ million} - \$2,000\text{ million} = -\$400\text{ million}\).

Therefore, the maximum possible volume of bank deposits decreases by $400 million.

A (1 mark)
- Correct calculation of initial deposits ($2,000M) vs new maximum deposits ($1,600M) yields a reduction of $400M.

Opportunity cost is the highest-valued option forgone.

Initially, Kelvin values Option X at $3,000, Option Y at $2,500, and Option Z at $1,800. If he chooses Option Y, his highest-valued alternative forgone is Option X ($3,000).

When Option X becomes unavailable, the remaining alternative to Option Y is Option Z ($1,800). Therefore, the opportunity cost of choosing Option Y changes from Option X to Option Z, which represents a decrease in opportunity cost.

A (1 mark): Correctly identifies that the opportunity cost decreases from Option X to Option Z.

When the price elasticity of demand is unitary (\(E_d = 1\)):

- (1) Total expenditure/revenue (\(P \times Q\)) remains constant when price changes because the percentage change in quantity demanded exactly offsets the percentage change in price. Thus, statement (1) is correct.
- (2) By definition, \(E_d = |\%\Delta Q / \%\Delta P| = 1\), meaning \(|\%\Delta Q| = |\%\Delta P|\). The percentage increase in price equals the percentage decrease in quantity demanded. Thus, statement (2) is correct.
- (3) When supply decreases, the equilibrium price increases and the equilibrium quantity decreases. The area representing consumer surplus unambiguously shrinks. Thus, statement (3) is correct.

D (1 mark): Correctly identifies that all three statements (1), (2), and (3) are correct.

Let's analyze the input requirements:

1. Absolute Advantage:
Country A requires fewer resources to produce 1 unit of toys (4 < 6) and 1 unit of watches (2 < 6). Hence, Country A has an absolute advantage in producing both goods. Statement (1) is correct.

2. Opportunity Costs:
- Country A: 1 unit of Toys = \(4/2 = 2\) units of Watches; 1 unit of Watches = \(2/4 = 0.5\) units of Toys.
- Country B: 1 unit of Toys = \(6/6 = 1\) unit of Watches; 1 unit of Watches = \(6/6 = 1\) unit of Toys.

Country B has a lower opportunity cost in producing toys (1 Watch < 2 Watches), so Country B has a comparative advantage in toys. Statement (2) is correct.

3. Terms of Trade:
The mutually beneficial terms of trade for 1 unit of toys are:
$$1 \text{ unit of Watches} < 1 \text{ unit of Toys} < 2 \text{ units of Watches}$$
Since 1.6 units of watches lies strictly between 1 and 2 units of watches, both countries gain from trade. Statement (3) is correct.

D (1 mark): Correctly identifies that statements (1), (2), and (3) are all correct.

1. Initial money supply \(M_1 = \text{Cash in public hands} + \text{Deposits} = \$200\text{ million} + \$1,000\text{ million} = \$1,200\text{ million}\).

2. The public receives $50 million from the bond sale and deposits the entire amount into the banking system. The new total reserves held by the banking system become:
$$\text{New Reserves} = \$300\text{ million} + \$50\text{ million} = \$350\text{ million}$$

3. With a legal reserve ratio of 20% (0.2) and no excess reserves, maximum total deposits will be:
$$\text{Maximum Deposits} = \frac{\$350\text{ million}}{0.2} = \$1,750\text{ million}$$

4. Cash held by the public remains $200 million. Thus, the new maximum money supply is:
$$\text{New Money Supply} = \$200\text{ million} + \$1,750\text{ million} = \$1,950\text{ million}$$

5. Change in money supply:
$$\Delta M = \$1,950\text{ million} - \$1,200\text{ million} = +\$750\text{ million}$$

C (1 mark): Correctly calculates the maximum increase in money supply as $750 million.

1. An increase in government expenditure on infrastructure increases aggregate demand (AD), shifting the AD curve to the right.
- This AD shift exerts upward pressure on both the price level and output.

2. An increase in the prices of imported raw materials increases firms' production costs, shifting the short-run aggregate supply (SRAS) curve to the left.
- This SRAS shift exerts upward pressure on the price level and downward pressure on output.

3. Combined short-run effect:
- Price level: Both shifts increase the price level, so the price level unambiguously rises.
- Output level: The AD increase expands output while the SRAS decrease contracts output. Without knowing the relative magnitude of the two shifts, the overall effect on output is indeterminate.

B (1 mark): Correctly deduces that the price level rises and the output level is indeterminate.

(a) Opportunity cost is the highest-valued option forgone.
Net value of Option 2 = $6,000 - $2,000 = $4,000.
Net value of Option 3 = $2,500 - $0 = $2,500.
Since Option 2 yields the highest net gain among forgone alternatives, the opportunity cost of choosing Option 1 is Option 2 (staying at a local resort hotel) and the $5,000 expenditure.

(b) The non-refundable deposit of $1,500 is a sunk cost because it cannot be recovered regardless of whether she goes on the cruise or not.
The remaining monetary cost she must pay to go on the cruise decreases from $5,000 to $3,500.
Therefore, the opportunity cost of choosing to go on the cruise decreases by $1,500.

(a)
- Identify Option 2 (local resort hotel) as the best alternative forgone (1 mark)
- Explain that Option 2 provides the highest net value / net gain ($4,000 > $2,500) among all forgone alternatives (1 mark)

(b)
- State that the non-refundable deposit is a sunk cost / unavoidable cost (1 mark)
- Explain that the additional/marginal monetary cost of taking the cruise decreases by $1,500 (from $5,000 to $3,500) (1 mark)
- Conclude that the opportunity cost of going on the cruise decreases (1 mark)

(a) When price falls and total revenue increases, the percentage increase in quantity demanded is greater than the percentage decrease in price. Therefore, the price elasticity of demand for sourdough bread is elastic (\(E_d > 1\)).

(b)
- An increase in flour price increases the production cost of sourdough bread, shifting the supply curve leftward from \(S_0\) to \(S_1\).
- Equilibrium price increases from \(P_0\) to \(P_1\), and equilibrium quantity decreases from \(Q_0\) to \(Q_1\).
- Since demand is elastic, the percentage decrease in quantity demanded is greater than the percentage increase in price. Thus, total revenue decreases (indicated by gain in revenue from higher price < loss in revenue from lower quantity).

(a)
- State elastic (\(E_d > 1\)) (1 mark)
- Explain that price and total revenue move in opposite directions / \% change in \(Q_d\) > \% change in \(P\) (1 mark)

(b)
Indicate in the diagram:
- Leftward shift of the supply curve (1 mark)
- Correct new equilibrium price \(P_1\) (higher) and quantity \(Q_1\) (lower) (1 mark)

Verbal elaboration:
- Explain that since demand is elastic, the percentage increase in price is smaller than the percentage decrease in quantity demanded, leading to a decrease in total revenue (1 mark)

(a) Required reserves = $1,200 \text{ million} \times 20\% = $240 \text{ million}.
Excess reserves = $300 \text{ million} - $240 \text{ million} = $60 \text{ million}.

(b) When the central bank purchases $40 million of government bonds from the public, $40 million of new reserves enter the banking system.
Maximum change in deposits = \(\frac{\text{Change in reserves}}{\text{Required reserve ratio}} = \frac{\$40 \text{ million}}{0.20} = \$200 \text{ million}\).
Since the public does not hold cash, Money Supply = Deposits.
Thus, the maximum possible increase in money supply is $200 million.

(c) The actual increase would be smaller if banks hold excess reserves (i.e. do not loan out all funds) OR if the public withdraws and holds cash currency (cash leakage).

(a)
- Excess reserves = $300m - ($1200m \times 20\%) = $60 million (1 mark)

(b)
- Banking multiplier = \(\frac{1}{20\%} = 5\) (1 mark)
- Change in money supply = \(\$40\text{m} \times 5 = \$200\text{ million}\) (2 marks: 1 for method, 1 for final value)

(c)
- State that banks hold excess reserves / public holds cash (cash leakage) (1 mark)

(a)
- An effective price ceiling \(P_c\) is set below the market equilibrium price \(P_0\).
- At \(P_c\), quantity demanded exceeds quantity supplied, creating a shortage.
- The quantity transacted falls from \(Q_0\) to \(Q_s\) (determined by the short side of the market, which is supply).
- Total rental expenditure was originally \(P_0 \times Q_0\). Under the ceiling, total expenditure becomes \(P_c \times Q_s\). Since both price and quantity transacted have fallen, total expenditure unambiguously decreases.

(b) Non-price rationing mechanisms include queuing (first-come, first-served), black market side-payments ("key money"), or landlord discrimination based on personal characteristics.

(a)
Indicate in the diagram:
- Price ceiling \(P_c\) below equilibrium price \(P_0\) (1 mark)
- Shortage with quantity transacted determined at \(Q_s\) (1 mark)

Verbal elaboration:
- Quantity transacted drops from \(Q_0\) to \(Q_s\) because supply contracts (1 mark)
- Total rental expenditure drops from \(P_0 \times Q_0\) to \(P_c \times Q_s\) because both price and transacted quantity decrease (1 mark)

(b)
- State one valid mechanism: queuing / waiting list / under-the-table payment (key money) / discrimination by landlords (1 mark)

(a)
- An increase in international energy and raw material prices raises production costs across the economy.
- The short-run aggregate supply curve shifts leftward from \(SRAS_0\) to \(SRAS_1\).
- At the original price level, there is excess demand in the goods and services market.
- As a result, the general price level increases from \(P_0\) to \(P_1\), while the real output decreases from \(Y_f\) to \(Y_1\) (stagflation).

(b)
- An increase in government expenditure on infrastructure directly raises aggregate demand (AD), shifting the AD curve rightward.
- This puts additional upward pressure on the price level, causing the general price level to increase even further.

(a)
Indicate in the diagram:
- Leftward shift of \(SRAS\) curve (1 mark)
- Higher general price level (\(P_1\)) and lower real output (\(Y_1\)) (1 mark)

Verbal elaboration:
- Higher input costs cause the \(SRAS\) curve to shift to the left (1 mark)
- Resulting in a higher price level and a lower output in the short run (1 mark)

(b)
- State that aggregate demand increases, leading to a further rise in the general price level (1 mark)

(a) Opportunity cost of an action is the highest-valued option forgone plus the explicit monetary cost. Since Option 2 is his second choice, the highest-valued alternative forgone is working at the bookstore (earning $240), along with the monetary payment of $300 for the workshop.

(b) Opportunity cost = forgone value of the best alternative + explicit monetary cost. When the bookstore wage increases to $350 and Option 2 remains his second choice (ranking unchanged), the value of the best alternative forgone rises from $240 to $350. Therefore, Kelvin's opportunity cost of attending the workshop increases.

(a)
- Working at the bookstore (earning $240) / best alternative forgone (1 mark)
- PLUS the tuition / monetary fee of $300 (1 mark)

(b)
- State that opportunity cost will increase / change. (1 mark)
- Explanation: Working at the bookstore remains the highest-valued alternative forgone. (1 mark)
- The value of this forgone alternative rises as the wage increases from $240 to $350, while explicit cost remains unchanged. (1 mark)

1. Diagram:
- Downward-sloping demand curve (D) and upward-sloping supply curve (S1).
- Leftward shift of the supply curve to S2.
- Correct original equilibrium (P1, Q1) and new equilibrium (P2, Q2) showing higher price and lower quantity.

2. Verbal explanation:
- Higher operating costs cause the market supply of coffee to decrease, shifting the supply curve leftwards from S1 to S2.
- The equilibrium price increases from P1 to P2, and the equilibrium quantity transacted decreases from Q1 to Q2.
- Since demand is price elastic (\(|E_d| > 1\)), the percentage decrease in quantity demanded is greater than the percentage increase in price.
- Loss in revenue due to fewer units sold outweighs the gain in revenue due to the higher unit price; hence, total revenue decreases.

Diagram (2 marks):
- Correct supply shift to the left with labeled axes and curves (1 mark)
- Correct indication of higher equilibrium price \(P_2 > P_1\) and lower equilibrium quantity \(Q_2 < Q_1\) (1 mark)

Verbal explanation (3 marks):
- Supply decreases / shifts to the left, causing equilibrium price to rise and equilibrium quantity to fall. (1 mark)
- Demand is elastic: \(%\Delta Q > %\Delta P\) (or quantity effect dominates price effect). (1 mark)
- Total revenue decreases. (1 mark)

(a) Required reserves = $1600 \text{ million} \times 20\% = $320 \text{ million}.
Excess reserves = Actual reserves - Required reserves = $400 - $320 = $80 \text{ million}.

(b) When $50 million is withdrawn, actual reserves decrease by $50 million to $350 million.
Since banks hold no excess reserves eventually, maximum deposits supported by $350 million of reserves:
\(\text{Maximum new deposits} = \frac{\$350\text{ million}}{20\%} = \$1750\text{ million}\).
Original deposits = $1600 million.
Maximum change in deposits = $1750 - $1600 = +$150 \text{ million}.
Since the public holds no cash, Money Supply (\(M_1\)) = Deposits.
Alternatively, considering the net change:
Initial excess reserves was $80 million. The withdrawal absorbs $50 million of reserves, leaving $30 million excess reserves to create credit.
Change in money supply = \(\frac{\$80 - \$50}{0.20} = +\$150 \text{ million}\).

Wait, let us check: if the question says 'all commercial banks hold no excess reserves initially', but actual reserves = 400 and required = 320, they held 80 million excess reserves initially. After withdrawal of 50 million, remaining reserves = 350 million. With 20% required reserve ratio and zero excess reserves, maximum deposits = 350 / 0.20 = 1750 million. Money supply increases by $150 million (or if initial deposits were 1600, change is +$150 million).

(a)
- \(\text{Required reserves} = \$1600 \times 20\% = \$320\text{ million}\)
- \(\text{Excess reserves} = \$400 - \$320 = \$80\text{ million}\) (1 mark)

(b)
- New reserves in the banking system = $400 - $50 = $350\text{ million} (1 mark)
- \(\text{Maximum total deposits} = \frac{\$350\text{ million}}{0.2} = \$1750\text{ million}\) (1 mark)
- Since \(\text{Money Supply} = \text{Deposits}\), \(\text{Maximum change in money supply} = \$1750 - \$1600 = +\$150\text{ million}\) / increases by $150 million. (2 marks)
[Full marks for direct calculation: \(\Delta MS = \frac{\text{Net excess reserves}}{r} = \frac{\$80 - \$50}{0.2} = +\$150\text{ million}\)]

(a) The Law of Diminishing Marginal Returns states that when increasing units of a variable factor are applied to a given quantity of fixed factor(s), the marginal product (or marginal output) of the variable factor will eventually decrease, holding technology and other factors constant.

(b) Calculating marginal output:
- 1st worker: 18 units
- 2nd worker: \(42 - 18 = 24\) units
- 3rd worker: \(69 - 42 = 27\) units
- 4th worker: \(92 - 69 = 23\) units
- 5th worker: \(110 - 92 = 18\) units
- 6th worker: \(120 - 110 = 10\) units

Marginal product reaches its maximum at the 3rd worker (27 units) and begins to decline when the 4th worker is employed (falling to 23 units). Therefore, diminishing marginal returns set in at the 4th worker.

(a)
- When additional units of a variable factor are added to a given quantity of fixed factor(s) (1 mark)
- The marginal product / marginal output will eventually decrease / decline (ceteris paribus). (1 mark)

(b)
- State that diminishing marginal returns set in at the 4th worker. (1 mark)
- Marginal output increases from the 1st to the 3rd worker (from 18 to 27 units). (1 mark)
- When the 4th worker is employed, marginal output begins to drop / decrease from 27 units to 23 units. (1 mark)

(a) (i) Absolute advantage refers to the ability of a country to produce a good using fewer resources (or less labour time) than another country.
Country A requires 10 hours of labour to produce 1 unit of smartphones, which is less than the 12 hours required by Country B. Therefore, Country A has an absolute advantage in producing smartphones.

(ii) In Country A:
Opportunity cost of 1 unit of garments = \(\frac{5}{10} = 0.5\) units of smartphones.
In Country B:
Opportunity cost of 1 unit of garments = \(\frac{4}{12} = \frac{1}{3} \approx 0.33\) units of smartphones.
Since Country B has a lower opportunity cost in producing garments (\(\frac{1}{3} < 0.5\)), Country B has a comparative advantage and should specialize in producing garments.

(b) The opportunity cost of producing 1 unit of smartphones is:
In Country A: \(\frac{10}{5} = 2\) units of garments.
In Country B: \(\frac{12}{4} = 3\) units of garments.
Therefore, the mutually beneficial terms of trade for 1 unit of smartphones is:
2 units of garments < 1 unit of smartphones < 3 units of garments.

(c) Diagram:
- Downward sloping domestic demand curve \(D\) and upward sloping domestic supply curve \(S\).
- Horizontal world supply curve at \(P_w = \$50\), and after tariff at \(P_t = \$60\).
- Domestic quantity supplied increases from \(Q_{s0}\) to \(Q_{s1}\); domestic quantity demanded decreases from \(Q_{d0}\) to \(Q_{d1}\).

Verbal elaboration:
(i) The domestic price of garments in Country A increases by the tariff amount, from \(P_w = \$50\) to \(P_t = \$60\).
(ii) At the higher price \(P_t\), domestic quantity demanded decreases from \(Q_{d0}\) to \(Q_{d1}\) while domestic quantity supplied increases from \(Q_{s0}\) to \(Q_{s1}\). Hence, the volume of imports drops from \((Q_{d0} - Q_{s0})\) to \((Q_{d1} - Q_{s1})\).
(iii) When the price increases and the quantity demanded decreases along the demand curve, whether total expenditure rises, falls, or remains unchanged depends on the price elasticity of demand (\(E_d\)):
- If \(E_d < 1\) (inelastic), total expenditure increases;
- If \(E_d > 1\) (elastic), total expenditure decreases;
- If \(E_d = 1\) (unitary elastic), total expenditure remains unchanged.

(d) After the tariff is imposed, the domestic price received by domestic producers increases from $50 to $60, and the domestic quantity supplied increases from \(Q_{s0}\) to \(Q_{s1}\). Since both the price and quantity sold by domestic producers increase, the total revenue of domestic garment producers (\(P \times Q\)) will definitely increase.

(a) (i)
- Definition of absolute advantage: Producing a good with fewer inputs / less time (1 mark)
- Identification that Country A takes less time (10 hours < 12 hours) (1 mark)

(ii)
- Calculation of opportunity cost of 1 unit of garments in Country A = 0.5 units of smartphones (1 mark)
- Calculation of opportunity cost of 1 unit of garments in Country B = 1/3 units of smartphones (1 mark)
- Conclusion: Country B specializes in garments because of lower opportunity cost (1 mark)

(b)
- Mutually beneficial terms of trade: 2 units of garments < 1 unit of smartphones < 3 units of garments (2 marks; 1 mark if weak inequalities are used or if expressed correctly per unit of garment)

(c)
Diagram (2 marks):
- Correct horizontal price line shift from \(P_w\) to \(P_t\) (1 mark)
- Correct indications of original and new import quantities \((Q_{d0}-Q_{s0})\) and \((Q_{d1}-Q_{s1})\) (1 mark)

Verbal elaboration (4 marks):
- (i) Domestic price increases from \(P_w\) to \(P_t\) (by $10) (1 mark)
- (ii) Domestic quantity demanded falls and domestic quantity supplied rises, so imports shrink (1 mark)
- (iii) Change in total consumer expenditure depends on price elasticity of demand (\(E_d\)) with correct conditions explained (2 marks)

(d)
- Stance: Total revenue increases (1 mark)
- Justification: Domestic price increases AND domestic quantity supplied increases, hence \(P \times Q\) rises (2 marks)

(a) Diagram:
- Downward sloping AD curve, upward sloping short-run aggregate supply curve (SRAS), and vertical long-run aggregate supply curve (LRAS).
- Leftward shift of the SRAS curve from \(SRAS_0\) to \(SRAS_1\).
- New equilibrium with higher price level \(P_1\) and lower real output \(Y_1 < Y_f\).

Verbal elaboration:
(i) The rise in raw material prices increases the per-unit cost of production across firms, shifting the SRAS curve to the left. As a result, the general price level rises from \(P_0\) to \(P_1\) (cost-push inflation).
(ii) Real output falls below the full-employment level from \(Y_f\) to \(Y_1\), creating a recessionary (deflationary) gap.
(iii) Because aggregate output drops, firms reduce their demand for labour, causing the unemployment rate to rise.

(b) (i) The central bank should buy government bonds in the open market.

(ii) Transmission mechanism:
- When the central bank buys government bonds from the public/commercial banks, the monetary base and commercial banks' excess reserves increase, leading to an expansion in the money supply (\(M_s\)).
- With money demand remaining unchanged, an excess supply of money lowers the nominal interest rate (\(r\)).
- A lower interest rate reduces the cost of borrowing, which increases private consumption expenditure (\(C\)) and investment expenditure (\(I\)).
- Since \(C\) and \(I\) are components of Aggregate Demand (\(AD = C + I + G + X - M\)), aggregate demand shifts rightward, restoring real output (\(Y\)) toward the full-employment level.

(c) (i) Transfer payments (e.g., social welfare allowances) are unilateral transfers without any corresponding production of goods or services or contribution to economic output in the current period. Therefore, they are not counted as government consumption expenditure (\(G\)) and do not directly enter the GDP calculation under the expenditure approach.

(ii) An increase in transfer payments raises the disposable post-tax, post-transfer income of low-income families without altering the income of higher-income groups proportionately. This narrows the income gap between the rich and the poor, reducing income inequality and causing the Gini coefficient (based on post-tax post-transfer income) to decrease.

(a)
Diagram (2 marks):
- Correct leftward shift of SRAS curve (1 mark)
- Correct indication of new equilibrium price level \(P_1 > P_0\) and output \(Y_1 < Y_f\) (1 mark)

Verbal elaboration (4 marks):
- Increase in production costs shifts SRAS leftward (1 mark)
- (i) General price level rises (1 mark)
- (ii) Real output falls / recessionary gap created (1 mark)
- (iii) Derived demand for labour drops, so unemployment rate rises (1 mark)

(b)
(i) Stance: Buy government bonds (1 mark)
(ii) Transmission mechanism (4 marks):
- Buying bonds increases bank reserves / money supply increases (1 mark)
- Interest rate falls due to excess money supply (1 mark)
- Lower interest rate stimulates consumption expenditure (\(C\)) / investment expenditure (\(I\)) (1 mark)
- Aggregate Demand increases (AD curve shifts right), raising real output (1 mark)

(c)
(i)
- Transfer payments involve no production of goods/services / no factor service rendered in return (1 mark)
- Hence not classified as government final consumption expenditure (\(G\)) / not part of GDP (1 mark)

(ii)
- Transfer payments raise the disposable income of lower-income households (1 mark)
- Income gap narrows / post-tax post-transfer income distribution becomes more even (1 mark)
- Gini coefficient decreases (1 mark)

(a) (i) In Country A: Opportunity cost of producing 1 unit of electric vehicle = \(40 / 10 = 4\) units of solar panels.
In Country B: Opportunity cost of producing 1 unit of electric vehicle = \(30 / 15 = 2\) units of solar panels.
Since Country B has a lower opportunity cost in producing electric vehicles (\(2 < 4\) units of solar panels), Country B has a comparative advantage in producing electric vehicles.

(ii) Mutually beneficial terms of trade for 1 unit of electric vehicle:
\(2\text{ units of solar panels} < 1\text{ unit of EV} < 4\text{ units of solar panels}\).

(b) Diagram:
- Draw downward-sloping domestic demand \(D\) and upward-sloping domestic supply \(S\).
- Draw horizontal world price line at \(P_w\) and after-tariff price line at \(P_w + t\).
- Show domestic quantity supplied increases from \(Q_{s1}\) to \(Q_{s2}\).
- Show domestic quantity demanded decreases from \(Q_{d1}\) to \(Q_{d2}\).
- Indicate deadweight loss as the two shaded welfare loss triangles: the production efficiency loss triangle and the consumption efficiency loss triangle.

Verbal explanation:
(i) With the tariff, the domestic market price rises from \(P_w\) to \(P_w + t\). Domestic quantity supplied (production) expands along the supply curve from \(Q_{s1}\) to \(Q_{s2}\) (increases).
(ii) Domestic quantity demanded contracts from \(Q_{d1}\) to \(Q_{d2}\). The volume of imports decreases from \((Q_{d1} - Q_{s1})\) to \((Q_{d2} - Q_{s2})\).
(iii) The tariff causes production distortion (producing at higher marginal cost than world price) and consumption distortion (marginal benefit exceeds world price), leading to a net loss in social surplus (deadweight loss).

(c) Yes, it will definitely decrease.
- After the tariff is imposed, the import price received by foreign sellers remains \(P_w\) (or the domestic price rises to \(P_w + t\)), while the volume of imports \(M = (Q_d - Q_s)\) strictly falls because \(Q_d\) decreases and \(Q_s\) increases.
- Total expenditure on imports at world price is \(P_w \times M\), which must decrease as \(M\) falls while \(P_w\) is constant.
- Alternatively, if expenditure is measured inclusive of tariff \((P_w + t) \times M\): Since demand is elastic, the rise in price leads to a more than proportionate fall in quantity demanded \(Q_d\), while domestic supply increases, causing import volume \(M\) to fall by an even greater proportion than price increase, so total expenditure on imported panels definitely decreases.

(d) AS-AD Diagram & Analysis:
- Direct production subsidies reduce the unit cost of production for firms, shifting the short-run aggregate supply curve to the right (from \(SRAS_1\) to \(SRAS_2\)).
- An increase in profits tax rate reduces after-tax profits/expected rate of return on investment, leading to a fall in investment expenditure (\(I\)), which shifts the aggregate demand curve to the left (from \(AD_1\) to \(AD_2\)).
- Price level: Both the rightward shift in \(SRAS\) and the leftward shift in \(AD\) exert downward pressure on the price level; hence, the general price level definitely decreases.
- Aggregate output: The rightward shift in \(SRAS\) tends to increase output, whereas the leftward shift in \(AD\) tends to decrease output; therefore, the effect on aggregate output is uncertain / depends on the relative magnitudes of the shifts.

(e) Extended Evaluation Essay:
1. Impact on Aggregate Output / Economic Growth:
- Subsidies to green technology lower costs and stimulate innovation/capacity, encouraging capital accumulation and potential output in the long run.
- However, higher profits tax dampens private investment incentives (\(I\)), and reducing welfare transfers lowers disposable income of low-income households, lowering private consumption expenditure (\(C\)). In the short run, aggregate demand falls, which may slow economic growth. Thus, the claim that it will improve economic growth is uncertain/debatable.
2. Impact on Income Equity:
- Higher profits tax rate is progressive and targets owners of capital/corporations, which may narrow the income gap.
- However, cutting welfare transfers directly harms lower-income families who rely on social safety nets, widening post-tax post-transfer income inequality.
- Thus, the overall effect on income equity depends on whether the equalizing effect of profits tax outweighs the regressive impact of welfare cuts.
3. Impact on Government Fiscal Balance:
- Higher profits tax revenues and reduced transfer payments directly improve the fiscal balance by raising government revenue and reducing fiscal outlays.
- On the other hand, production subsidies increase government expenditure.
- Overall fiscal position improves if the additional tax revenue and welfare savings exceed the subsidy disbursements.
Conclusion: The statement is oversimplified; positive outcomes on growth and equity are not guaranteed and involve significant trade-offs.

(a) (i)
- Country A: Opportunity cost of 1 EV = \(40/10 = 4\) units of solar panels (1)
- Country B: Opportunity cost of 1 EV = \(30/15 = 2\) units of solar panels (1)
- Stating that Country B has a comparative advantage because its opportunity cost is lower (1)

(a) (ii)
- 2 units of solar panels < 1 unit of EV < 4 units of solar panels (2)
[1 mark for correct numbers without strict inequality / bounds]

(b)
Indicate in diagram:
- Correct axes (Price, Quantity) and initial equilibrium with \(P_w\), \(Q_{s1}\), \(Q_{d1}\) (1)
- Upward shift of price line to \(P_w + t\) showing \(Q_{s2}\) and \(Q_{d2}\) (1)
- Correctly shaded deadweight loss / welfare loss area (two triangles) (1)
Verbal elaboration:
- Domestic production increases from \(Q_{s1}\) to \(Q_{s2}\) (1)
- Import volume decreases from \((Q_{d1} - Q_{s1})\) to \((Q_{d2} - Q_{s2})\) (1)
- Explaining deadweight loss arises from production inefficiency (higher domestic production cost than world price) and consumption distortion (1)

(c)
- Stating that import volume \(M = Q_d - Q_s\) decreases significantly (1)
- Explaining that since \(P_w\) is constant for foreign suppliers and \(M\) falls, expenditure paid to foreign producers decreases / or since demand is elastic, \(\%\Delta Q_d > \%\Delta P\) combined with rising \(Q_s\) causes \(M\) to fall by a greater percentage than the price increase (1)
- Concluding that total expenditure on imported solar panels definitely decreases (1)

(d)
Indicate in diagram:
- Rightward shift of \(SRAS\) curve (1)
- Leftward shift of \(AD\) curve (1)
- Correct new equilibrium showing lower price level \(P\) and uncertain/indicated output \(Y\) (1)
Verbal elaboration:
- Subsidies reduce production cost \(\rightarrow SRAS\) shifts right (1)
- Higher profits tax reduces investment expenditure \(\rightarrow AD\) shifts left (1)
- Price level definitely decreases, but aggregate output is indeterminate/uncertain depending on relative shift magnitudes (1)

(e) Extended Evaluation Essay (8 marks content + 2 marks Effective Communication):
Content (Max 8 marks):
- Economic growth / output (Max 3 marks):
* Positive channel: Subsidies promote green tech industry and potential growth (1)
* Negative channel: Profit tax reduces \(I\) and welfare cuts reduce \(C\), contracting \(AD\) (1)
* Stance/Synthesis: Net short-run vs long-run growth effect is ambiguous (1)
- Income equity (Max 3 marks):
* Progressive impact: Higher profits tax reduces post-tax income of high-income capital owners (1)
* Regressive impact: Reductions in welfare transfers worsen disposable income of low-income groups (1)
* Stance/Synthesis: Overall impact on Gini coefficient/equity is ambiguous (1)
- Fiscal balance (Max 3 marks):
* Positive for balance: Higher profits tax increases revenue; welfare cuts reduce outlays (1)
* Negative for balance: Subsidies increase fiscal spending (1)
* Net fiscal condition evaluation (1)

Effective Communication (EC: 0–2 marks):
- 2 marks: Well-structured, coherent arguments using appropriate economic terminology with clear logical links across all three dimensions.
- 1 mark: Comprehensible response with minor structural weaknesses or limited economic jargon.
- 0 marks: Disorganized, irrelevant points, or severe conceptual flaws.