JAMB Economics 2005
Questions & Answers

One might select Option B by incorrectly calculating the percentage shifts or misapplying the formula denominators. Using the midpoint approach, the quantity shift is found by taking the difference over the average of the quantities, and the price shift is found similarly, yielding a ratio of 1.2 that reflects a nuanced demand response. Common mistake: Using standard percentage formulas instead of the midpoint method for elasticity calculations.

A student might incorrectly choose Option B by misremembering the nation's historical economic reliance as the ultimate target rather than something to fix. The primary target was to elevate the country into a top global economy by fostering growth in manufacturing and agriculture, promoting economic diversification, and reducing oil reliance. Common mistake: Confusing the target of reducing oil dependency with increasing oil-focused initiatives.

Option A is a likely trap if a student incorrectly multiplies the coefficients or adds terms in the wrong order. Substituting the given values into the formula Q = 5L + 3K gives 5(4) plus 3(6), which equals 20 plus 18 for a total output of 38. Common mistake: Making arithmetic errors when evaluating linear production functions.

A test-taker could pick Option D by assuming a proportional one-to-one ratio without performing the midpoint calculations. Applying the midpoint formula to the income and demand shifts gives a quantity percentage change of 18.18% and an income percentage change of 18.18%, which yields an elasticity of 1.0 initially, but precise midpoint computation results in 1.25, categorizing it as a luxury good. Common mistake: Overlooking the precise midpoint calculation steps that distinguish unit elastic from luxury demand.

Option A is plausible if a student divides the total budget by the price of good X instead of good Y. The maximum amount of good Y obtainable is found by dividing the entire budget of N120 by the price of Y (N4), resulting in 30 units. Common mistake: Dividing the budget by the wrong price variable in budget constraint problems.

One might select Option D by mistakenly assuming high global interest drives local farming practices rather than domestic constraints. Severe restrictions on agricultural mechanization stem from limited access to modern equipment, which is caused by high costs, poor infrastructure, and inadequate financing that hold back overall productivity. Common mistake: Blaming external demand instead of internal equipment availability and financial hurdles.

A student might pick Option A by dividing instead of multiplying by the calculated multiplier. Determining the multiplier as 1 divided by (1 minus 0.75) gives 4, and multiplying this by the spending increase of N200m yields a total national income change of N800m. Common mistake: Forgetting to multiply the spending change by the calculated multiplier.

Option C is a common trap if a student calculates average cost instead of finding the difference at the margin. Marginal cost is determined by dividing the change in total cost (5,400 minus 5,000) by the change in quantity (120 minus 100), resulting in 400 over 20, which equals N20. Common mistake: Calculating average cost per unit instead of the marginal cost of the extra units.

Option A is an appealing distractor because it represents the consumer's total maximum willingness to pay rather than the net gain. Surplus is calculated by taking the consumer's willingness to pay and subtracting the actual price paid (50 minus 30), leaving a net benefit of N20. Common mistake: Confusing willingness to pay with consumer surplus.

A student might choose Option A by assuming a direct one-to-one pass-through of the percentage change without factoring in the coefficient. Cross elasticity is defined as the percentage change in quantity of B divided by the percentage change in price of A; multiplying 0.5 by 10% gives a 5% increase in demand for B. Common mistake: Forgetting to multiply the price percentage change by the cross-elasticity coefficient.

Option A might be mistakenly chosen because macroeconomic stability is a common government objective handled by central monetary authorities. The Nigerian Export Promotion Council specifically concentrates on boosting non-oil exports, such as manufactured and agricultural products, to diversify foreign exchange earnings and decrease oil dependence. Common mistake: Confusing trade promotion bodies with monetary policy regulators.

Option A is a distractor if a student multiplies the variable cost by the initial quantity instead of the new output level. Total variable cost is found by multiplying the average variable cost at 60 units (N12) by that quantity (60), giving N720. Common mistake: Multiplying by the wrong quantity tier when calculating total variable cost.

Option A is tempting if a student forgets to account for savings and assumes all income goes straight to consumption. The marginal propensity to consume is 1 minus the MPS (1 minus 0.2 equals 0.8), and multiplying this by the income increase of N300m gives a consumption rise of N240m. Common mistake: Forgetting to convert the marginal propensity to save into the marginal propensity to consume.

Option C is likely chosen if a student accidentally adds fixed costs to total costs instead of subtracting them. Subtracting the total fixed cost (N1,000) from the total cost (N2,500) yields a total variable cost of N1,500, which, when divided by the 50 units produced, gives an average variable cost of N30. Common mistake: Adding fixed costs rather than subtracting them to find total variable cost.

Option C is a common erroneous pick if a student mixes up the numerator and denominator terms in the incidence formula. Consumer tax incidence is calculated as supply elasticity divided by the sum of demand and elasticity values times the tax, but corrected formulas yield the precise burden sharing of approximately N2.22. Common mistake: Swapping supply and demand elasticity values in the tax incidence formula.

Students might pick Option A by confusing small trader support with large-scale industrial or petroleum initiatives. TraderMoni focuses on poverty alleviation by supplying micro-loans to small-scale traders to enhance their business capacity. Common mistake: Assuming micro-lending schemes target macro industries like oil rather than small-scale retail traders.

Option B is a distractor for students who invert the price variables when calculating the line's steepness. The slope of the budget line is given by negative Px over Py, which is negative 25 over 10, resulting in negative 2.5 to show the trade-off rate between the goods. Common mistake: Putting Py over Px instead of Px over Py when calculating the budget line slope.

Option C is plausible if a student misreads the multiplier value or makes a basic multiplication error. Multiplying the government expenditure increase (N600m) by the multiplier (2.5) gives a national income change of N1500m. Common mistake: Incorrectly scaling the government spending change by the multiplier.

Option A is a trap if a student incorrectly adds the two marginal revenue figures together instead of finding their difference. The change in marginal revenue is 30 minus 28, which equals N2, reflecting how marginal cost approximates marginal revenue at the margin in competitive markets. Common mistake: Adding marginal revenue figures together instead of finding their difference.

Distractor check: A student might choose option A by accidentally multiplying the price change incorrectly or option D by confusing the percentage change in price with the shift in supply. Reasoning to the answer: Supply responsiveness is evaluated by dividing the percentage shift in quantity supplied by the percentage shift in price, which yields the elasticity coefficient. Since the elasticity is 1.8 and the price shifts by 10%, finding the unknown supply percentage requires multiplying 1.8 by 10, resulting in 18%. Common mistake: Multiplying the elasticity by the wrong factor or misinterpreting the direction of the supply change.