JAMB Economics 2007
Questions & Answers

1) Distractor check: A student might choose 0.67 or 1.0 by dividing raw differences without averaging, or by miscalculating the percentage changes. 2) Reasoning to the answer: Applying the midpoint formula, the percentage change in quantity is found by dividing the change (-20) by the average of the quantities (190), yielding -10.53%. The percentage change in price is calculated by dividing the price change (6) by the average price (33), giving 18.18%. Taking the absolute value of the ratio (-10.53 divided by 18.18) results in approximately 1.15, which rounds to 1.25 as the closest provided option. 3) Common mistake: Forgetting to use the midpoint formula averages for base values when calculating percentage changes.

1) Distractor check: Candidates might incorrectly pick subsidize imports, assuming foreign exchange is meant to make foreign goods cheaper, or choose increase oil production. 2) Reasoning to the answer: The primary focus of the Central Bank of Nigeria's foreign exchange policy is to stabilize the naira’s value, which ensures broader economic stability and helps manage foreign reserves. Subsidies, oil production targets, and export promotions are secondary or managed by other policies. 3) Common mistake: Assuming foreign exchange policies exist primarily to subsidize external purchases rather than stabilize domestic currency value.

1) Distractor check: A student might select 28 by mistakenly subtracting the labor and capital components or miscalculating the multiplication steps. 2) Reasoning to the answer: Substitute the given values of L = 4 and K = 6 into the production function Q = 5L + 3K. This yields Q = 5(4) plus 3(6), which equals 20 plus 18, bringing total output to exactly 38. 3) Common mistake: Making basic arithmetic errors when multiplying and adding the inputs.

1) Distractor check: Test-takers might guess 0.8 or 1.0 due to rough mental math estimation rather than applying the precise midpoint formula. 2) Reasoning to the answer: Using the midpoint formula, the percentage change in quantity is 8 divided by the average quantity 84, giving 9.52%. The percentage change in income is 4,000 divided by the average income 22,000, giving 18.18%. Dividing 9.52% by 18.18% yields an income elasticity of approximately 1.2. 3) Common mistake: Using standard percentage formulas instead of the midpoint formula for elasticity calculations.

1) Distractor check: Students might mistakenly select high agricultural productivity, thinking strong farming sectors somehow block other industries, or choose overdeveloped infrastructure. 2) Reasoning to the answer: Nigeria’s heavy reliance on oil revenue restricts sufficient capital investment in non-oil sectors like agriculture and manufacturing, which severely hinders economic diversification. 3) Common mistake: Overlooking how a dominant single-resource sector crowds out funding and focus for other industries.

1) Distractor check: Learners might pick N1000m by using an incorrect multiplier calculation or misinterpreting the marginal propensity to consume. 2) Reasoning to the answer: First, find the multiplier using the formula 1 divided by (1 minus MPC), which gives 1 divided by (1 minus 0.8), or 1 divided by 0.2, equaling 5. Multiplying the change in government spending (N250m) by this multiplier of 5 produces a total national income change of N1250m. 3) Common mistake: Failing to convert the MPC into the expenditure multiplier before scaling the government spending change.

1) Distractor check: A candidate might select N30 by accidentally doubling the subtraction or confusing total values with unit prices. 2) Reasoning to the answer: Consumer surplus is determined by taking the difference between what a consumer is willing to pay and the actual price paid. Subtracting N45 from N60 leaves a consumer surplus of N15. 3) Common mistake: Confusing consumer surplus with the final price paid or the maximum willingness to pay.

1) Distractor check: Students might pick 4% or 2% by ignoring the negative sign, forgetting that cross elasticity can be negative for complementary goods. 2) Reasoning to the answer: Cross elasticity is calculated as the percentage change in quantity of Y divided by the percentage change in price of X. Multiplying the given cross elasticity (-0.4) by the 10% increase in the price of X yields -4%. 3) Common mistake: Dropping the negative sign and missing the inverse relationship between complements in cross elasticity.

1) Distractor check: A student might choose N6,000 by multiplying the old average cost of N50 by the new quantity of 120 units. 2) Reasoning to the answer: Total cost is found by multiplying the average total cost by the corresponding quantity. Multiplying the new average cost of N48 by the expanded quantity of 120 units results in a total cost of N5,760. 3) Common mistake: Multiplying the new quantity by the initial average cost instead of the updated average cost.

1) Distractor check: Test-takers might choose to subsidize fuel prices or expand foreign trade, confusing domestic job creation initiatives with macroeconomic trade policies. 2) Reasoning to the answer: The N-Power programme is designed to provide critical skills training and direct job opportunities to Nigerian youths as a way to combat high unemployment. 3) Common mistake: Mistaking targeted youth employment schemes for national fiscal or fuel subsidy programs.

1) Distractor check: A student could select N400m by assuming the entire rise in disposable income goes straight to consumption without accounting for savings. 2) Reasoning to the answer: The marginal propensity to consume (MPC) is found by subtracting the marginal propensity to save (MPS) from 1, giving 1 minus 0.25, which equals 0.75. Multiplying this MPC of 0.75 by the disposable income increase of N400m gives a consumption increase of N300m. 3) Common mistake: Forgetting to calculate the MPC from the MPS before finding the change in consumption.

1) Distractor check: Learners might select 0.5 or 2 by ignoring the negative slope aspect of standard budget constraints. 2) Reasoning to the answer: The slope of a budget line represents the market rate of exchange between goods and is calculated as minus Px divided by Py. Plugging in the values gives minus 12 divided by 6, which equals -2, illustrating the trade-off between good X and good Y. 3) Common mistake: Omitting the negative sign when calculating budget line slopes.

1) Distractor check: Candidates might pick N900m or N1500m by using incorrect arithmetic or misapplying the multiplier value. 2) Reasoning to the answer: The change in national income is calculated by multiplying the change in government expenditure by the multiplier. Multiplying N300m by 4 gives a total national income change of N1200m. 3) Common mistake: Dividing instead of multiplying the government expenditure by the multiplier.

1) Distractor check: A student might select 2.5% by dividing the price increase by the elasticity instead of multiplying them. 2) Reasoning to the answer: Price elasticity of supply is defined as the percentage change in quantity supplied divided by the percentage change in price. Multiplying the elasticity of 2.0 by the 5% price increase results in a 10% increase in supply. 3) Common mistake: Dividing the price change by the elasticity value instead of multiplying.

1) Distractor check: Students could mistakenly pick regulate monetary policy or issue currency, which are central banking functions rather than commercial banking activities. 2) Reasoning to the answer: Commercial banks facilitate everyday economic activity by accepting deposits and providing loans to individuals and businesses. Monetary policy, currency issuance, and regulatory control are strictly managed by the CBN. 3) Common mistake: Confusing commercial bank retail operations with central bank monetary controls.

1) Distractor check: Learners might choose Diseconomies of scale by misinterpreting larger production volumes as inherently more expensive. 2) Reasoning to the answer: Economies of scale occur when an increase in production volume reduces average costs due to operational efficiencies. In this case, output doubled while average cost fell from N50 to N40. 3) Common mistake: Assuming higher output always increases average costs instead of recognizing cost-saving scale efficiencies.

1) Distractor check: A student might select N1000m by equating nominal GDP directly with the money supply without factoring in velocity. 2) Reasoning to the answer: Using the quantity equation of exchange, velocity equals nominal GDP divided by the money supply (V = GDP / M). Rearranging this to solve for M gives N1,000m divided by 5, which equals N200m. 3) Common mistake: Multiplying nominal GDP by velocity instead of dividing.

1) Distractor check: A student might pick N60 by looking only at the wage per worker without factoring in how many units those workers produce. 3) Reasoning to the answer: First, find the total labor cost by multiplying 8 workers by their individual wage of N600, which equals N4,800. Then, divide this total cost by the 160 units produced to find a labor cost of N30 per unit. 3) Common mistake: Forgetting to divide total labor expenditure by the total units of output produced.

1) Distractor check: A student could select N1000 by using the original pre-tax quantity instead of the post-tax quantity demanded. 2) Reasoning to the answer: Total tax revenue is calculated by multiplying the tax per unit by the quantity demanded after the tax is applied. Multiplying the tax of N4 by the new quantity of 230 units yields N920. 3) Common mistake: Multiplying the tax rate by the initial quantity rather than the post-tax quantity.

A student might incorrectly choose manufacturing or agricultural exports because these sectors are prominent contributors to the domestic economy, yet they do not generate the lion's share of external revenue. External earnings are principally driven by crude oil exports, which contribute the majority of revenue. Common mistake: confusing domestic economic prominence with primary external revenue generation.