Economics 2023 Jamb Examination

A perfect market requires homogeneous goods, perfect knowledge, and many buyers and sellers to ensure no single agent can influence price.
Lack of homogeneity contradicts the requirement that all units of the good must be identical. Homogeneity ensures buyers treat products as perfect substitutes and price is uniform across the market.
Therefore, lack of homogeneity is the only option that does NOT describe a condition for a perfect market.

Consumer equilibrium occurs where the indifference curve is tangent to the budget line.
At point k, the budget line just touches the highest attainable indifference curve without crossing it. This tangency represents the point where the marginal rate of substitution equals the price ratio, fulfilling the condition for equilibrium.
The other points either lie on lower indifference curves or do not reflect tangency.

The national income identity is:\[ Y = C + I + G \]Substituting the consumption function:\[ Y = (100 + 0.75Y) + 50 + 200 \]\[ Y = 350 + 0.75Y \]Subtracting 0.75Y from both sides:\[ Y - 0.75Y = 350 \]\[ 0.25Y = 350 \]\[ Y = \dfrac{350}{0.25} = 1400 \]The equilibrium level of national income is therefore 1400.

Elasticity of demand is calculated using the percentage method:\[ E_d = \dfrac{\Delta Q / Q}{\Delta P / P} \]\[ \Delta Q = 30 - 20 = 10, \, Q = 20 \]\[ \Delta P = 6 - 8 = -2, \, P = 8 \]\[ E_d = \dfrac{10/20}{-2/8} = \dfrac{0.5}{-0.25} = -2 \]The negative sign indicates the inverse relationship between price and quantity, but elasticity is expressed as an absolute value.
Thus, elasticity = 2.

In most West African economies, agriculture remains the dominant employer of labour, particularly in rural areas.
Approximately 60% of the labour force is engaged in farming-related activities due to limited industrialisation and reliance on primary production.
The other options relate to land usage and market size, which do not consistently reflect the 60% proportion.

The downward slope of the demand curve is primarily explained by diminishing marginal utility.
As a consumer buys more units of a good, the additional satisfaction from each unit decreases. Therefore, consumers are only willing to purchase extra units at lower prices.
This behavioural principle results in an inverse relationship between price and quantity demanded.

The multiplier measures how much national income changes in response to a change in autonomous spending such as investment or government expenditure.
Formally, it is expressed as:\[ k = \dfrac{\Delta Y}{\Delta A} \]Thus, it is the ratio of the change in output (Y) to a change in autonomous spending, matching option C.

Natural growth rate of population refers to population increase excluding migration.
It is defined as the difference between birth rate and death rate.
This measure captures how population would grow purely from natural demographic processes.

Balance of payments deficits generally arise from excessive import dependence, low export diversification, and heavy external debt servicing.
Export promotion improves foreign exchange earnings and therefore does not cause deficits.
The remaining options represent structural weaknesses that can contribute to a BOP deficit.

The standard two-by-two international trade model assumes two countries, two goods, and comparative advantage as the basis for trade gains.
Both countries benefit from trade, but the magnitude of the gains each receives depends on the terms of trade, which determine how many units of one good exchange for another.
This aligns with the principle that although gains are mutual, their distribution is shaped by relative prices.