Consumer Behaviour: Utility Analysis, Indifference Curve and Consumer Equilibrium Questions

Question 1

Explain total utility and marginal utility and their relationship.

Accepted Answer

Total utility is total satisfaction from consuming a given quantity of a good, while marginal utility is additional satisfaction from one more unit. MU is the change in TU when one more unit is consumed. When MU is positive, TU increases; when MU becomes zero, TU is maximum; and when MU is negative, TU starts decreasing. This relationship explains consumer behaviour under diminishing MU.

Question 2

Define utility.

Accepted Answer

Utility is the power of a commodity to satisfy human wants.

Question 3

Define marginal utility.

Accepted Answer

Marginal utility is the additional satisfaction obtained from consuming one more unit of a commodity.

Question 4

State the law of diminishing marginal utility.

Accepted Answer

As consumption of a commodity increases, marginal utility derived from each successive unit goes on diminishing, other things remaining constant.

Question 5

What is an indifference curve?

Accepted Answer

An indifference curve shows different combinations of two goods that give the consumer the same level of satisfaction.

Question 6

What is a budget line?

Accepted Answer

Budget line shows all combinations of two goods that can be purchased with given income at given prices.

Question 7

State the condition of consumer equilibrium under equi-marginal utility.

Accepted Answer

Consumer equilibrium occurs when marginal utility per rupee is equal for all goods, i.e., MUx/Px = MUy/Py = ... and the income is fully spent.

Question 8

Explain law of diminishing marginal utility and its importance.

Accepted Answer

The law states that marginal utility of successive units of a commodity diminishes as consumption increases, other things constant. It is important because it explains the downward sloping demand curve and forms the basis of consumer equilibrium under utility approach. It also supports the law of equi-marginal utility by showing why consumers reallocate expenditure to equalise marginal utility per rupee.

Question 9

Explain consumer equilibrium under the law of equi-marginal utility.

Accepted Answer

Under equi-marginal utility, a consumer maximises satisfaction when marginal utility per rupee spent is equal across goods. The equilibrium condition is MUx/Px = MUy/Py = ... and the consumer spends the whole income. If MUx/Px is higher than MUy/Py, the consumer shifts spending towards X until the ratios become equal.

Question 10

Explain indifference curve and its properties.

Accepted Answer

An indifference curve shows combinations of two goods giving the same satisfaction. It is **downward sloping** because to maintain satisfaction, more of one good is needed when less of the other is consumed. It is **convex to origin** due to diminishing MRS. Higher IC indicates higher satisfaction, and indifference curves **do not intersect** because intersection would contradict preference ordering.

Question 11

Explain budget line and its slope.

Accepted Answer

Budget line represents all affordable combinations of two goods given income and prices. Its equation is PxX + PyY = M. The slope of budget line is -Px/Py, showing the rate at which the market allows the consumer to substitute one good for another. A change in income shifts the budget line, while a change in price changes its slope.

Question 12

Explain consumer equilibrium under indifference curve approach.

Accepted Answer

Consumer equilibrium occurs where the budget line is tangent to the highest attainable indifference curve. At tangency, MRSxy equals Px/Py (slope of budget line), meaning the consumer’s willingness to substitute equals the market trade-off. The IC must be convex at tangency to ensure stable equilibrium and maximum satisfaction.

Question 13

Explain utility analysis. Discuss total utility, marginal utility and law of diminishing marginal utility with suitable points.

Accepted Answer

Utility analysis explains consumer behaviour by assuming that consumers purchase goods to maximise satisfaction (utility) subject to limited income and given prices. Utility is the power of a commodity to satisfy human wants and it is subjective.

**Total utility (TU)** is the total satisfaction obtained from consuming a certain number of units of a commodity. **Marginal utility (MU)** is the additional satisfaction obtained from consuming one more unit. MU is the change in TU when consumption increases by one unit. When MU is positive, TU increases; when MU becomes zero, TU is maximum; and when MU becomes negative, TU starts falling.

**Law of diminishing marginal utility (DMU):** The law states that as a consumer consumes more and more units of a commodity, the marginal utility derived from each successive unit goes on diminishing, other things remaining constant. This happens because the intensity of want decreases with each additional unit.

**Importance:** DMU explains why demand curve slopes downward and forms the basis of consumer equilibrium and the law of equi-marginal utility. It helps understand why consumers diversify consumption and allocate income among different goods to maximise satisfaction.

Question 14

Explain consumer equilibrium under utility (Marshallian) approach. State the condition for equilibrium for one good and two goods.

Accepted Answer

Consumer equilibrium means a situation where a consumer obtains maximum satisfaction from a given income at given prices and has no incentive to change the combination of goods purchased.

**One commodity equilibrium:** If a consumer spends all income on one good X, equilibrium is reached when marginal utility of X equals its price (in money terms): MUx = Px. In marginal utility per rupee form, MUx/Px = 1. If MUx is greater than Px, the consumer will buy more; if MUx is less than Px, the consumer will buy less, and adjustment continues until equality is achieved.

**Two (or more) commodities equilibrium (Law of equi-marginal utility):** When the consumer buys two goods X and Y, maximum satisfaction occurs when marginal utility per rupee is equal for both goods:
MUx/Px = MUy/Py (and similarly for other goods) and the consumer spends the whole income.

If MUx/Px is greater than MUy/Py, the consumer should spend more on X and less on Y. Due to diminishing marginal utility, MU of X falls and MU of Y rises until the ratios become equal. Thus, the equality of marginal utility per rupee ensures maximum satisfaction.

Question 15

Explain indifference curve analysis and consumer equilibrium. Describe properties of indifference curves and the equilibrium condition.

Accepted Answer

Indifference curve analysis explains consumer behaviour by using ordinal utility, where utility cannot be measured in numbers but preferences can be ranked. An indifference curve (IC) shows different combinations of two goods that give the consumer the same satisfaction, so the consumer is indifferent among them.

**Properties of indifference curves:** ICs are downward sloping because to keep satisfaction constant, more of one good is needed when less of the other is consumed. ICs are convex to the origin due to diminishing marginal rate of substitution (MRS). Higher ICs represent higher satisfaction. Two ICs cannot intersect because intersection would contradict the ranking of preferences.

**Budget line:** Budget line shows all combinations of two goods that can be purchased with given income and prices: PxX + PyY = M. Its slope is -Px/Py.

**Consumer equilibrium:** The consumer reaches equilibrium where the budget line is tangent to the highest attainable indifference curve. At this point, the consumer maximises satisfaction subject to budget constraint.

**Equilibrium condition:** MRSxy = Px/Py, and the IC must be convex at the tangency point to ensure stable equilibrium. This means the consumer’s willingness to substitute equals the market rate of substitution, giving maximum satisfaction.

Consumer Behaviour: Utility Analysis, Indifference Curve and Consumer Equilibrium

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