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Question 32 of 35

Q.Discuss briefly the following properties of an indifference curve, using diagram:

(a) Convexity to origin
(b) Downward sloping from left to right
Uttarakhand UbseCBSE Class XII Board 2019Subjective· 6mImportance★★★★★
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An indifference curve represents combinations of two goods that yield the same utility. Its downward slope reflects that to maintain constant utility, giving up one good requires gaining another. Its convexity to the origin is due to the diminishing marginal rate of substitution, meaning consumers are willing to give up less of a good as they have more of it.

An indifference curve is a fundamental tool in consumer theory, illustrating various combinations of two goods that provide a consumer with the same level of satisfaction or utility. Because all points on a single indifference curve yield equal utility, a consumer is indifferent between any of these combinations. The shape and slope of these curves reveal important aspects of consumer preferences.

Let's discuss two key properties:

(a) Convexity to the Origin

The property of convexity to the origin is rooted in the concept of the Diminishing Marginal Rate of Substitution (DMRS).

Note

The Marginal Rate of Substitution (MRS) is the rate at which a consumer is willing to give up units of Good Y for an additional unit of Good X, while remaining on the same indifference curve (i.e., maintaining the same level of utility). Mathematically, it is the absolute value of the slope of the indifference curve at any point:

MRSXY=∣ΔYΔX∣MRS_{XY} = \left| \frac{\Delta Y}{\Delta X} \right|

The principle of DMRS states that as a consumer consumes more and more of one good (say, Good X), their willingness to give up units of the other good (Good Y) for an additional unit of Good X decreases. This happens because as the consumer has more of Good X, its marginal utility (the additional satisfaction from one more unit) tends to fall, while the marginal utility of Good Y (which is becoming relatively scarcer) tends to rise. Consequently, the consumer demands less and less of Good Y to compensate for an additional unit of Good X.

On a diagram, with Good X on the horizontal axis and Good Y on the vertical axis, this diminishing MRS is reflected in the indifference curve being convex to the origin. As we move down along the curve from left to right, the slope of the curve (which represents the MRS) becomes progressively flatter. This indicates that the consumer is willing to give up smaller and smaller amounts of Good Y for each additional unit of Good X to maintain the same level of satisfaction. For instance, moving from a point with a lot of Y and little X to a point with more X and less Y, the consumer will give up a large amount of Y for a small amount of X initially. But as X becomes more abundant and Y scarcer, they will only give up a small amount of Y for an additional unit of X.

(b) Downward Sloping from Left to Right

This property stems from the assumption of monotonic preferences, which implies that "more is better." Consumers generally prefer more of a good to less of it. …

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