UPSC MainsECONOMICS-PAPER-I201910 Marks150 Words
Q1.

Under competition, the cost function is given as C(y) = y² +1, where y is output. Derive the inverse supply curve and show how the supply curve looks like.

How to Approach

This question tests the understanding of cost and supply curves in microeconomics. The approach should involve first deriving the marginal cost (MC) from the given cost function, then equating MC to price (P) to find the firm’s supply function. Finally, rearranging the supply function will yield the inverse supply curve. The shape of the supply curve can then be described based on the derived function. Focus on clarity and mathematical accuracy.

Model Answer

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Introduction

In economics, understanding the relationship between cost, supply, and price is fundamental to analyzing market behavior. The supply curve represents the quantity of a good or service that producers are willing to offer at various prices. The cost function, which details the costs incurred by a firm at different output levels, is a crucial determinant of the supply curve. Given the cost function C(y) = y² + 1, where y represents output, this answer will derive the inverse supply curve and illustrate its characteristics, demonstrating the link between production costs and market supply.

Derivation of the Supply Curve

The supply curve is derived from the firm’s cost structure. Specifically, a firm in a competitive market will supply the quantity where marginal cost (MC) equals price (P). Therefore, to derive the supply curve, we first need to calculate the marginal cost.

1. Calculating Marginal Cost (MC)

Marginal cost is the change in total cost resulting from producing one additional unit of output. Mathematically, it is the derivative of the cost function with respect to output (y).

C(y) = y² + 1

MC = dC(y)/dy = 2y

2. Deriving the Supply Function

In a perfectly competitive market, firms maximize profit by producing where P = MC. Therefore, the supply function is given by:

P = 2y

3. Deriving the Inverse Supply Curve

The inverse supply curve expresses price as a function of quantity. To obtain this, we rearrange the supply function to solve for P:

y = P/2

Therefore, the inverse supply curve is: P = 2y

Shape of the Supply Curve

The inverse supply curve, P = 2y, is a linear function with a positive slope. This indicates that as the quantity supplied (y) increases, the price (P) also increases. The slope of the supply curve is 2, meaning that for each additional unit of output, the price must rise by 2 to cover the increasing marginal cost of production. This is a typical upward-sloping supply curve observed in competitive markets.

Graphical Representation

The supply curve can be visualized as a straight line originating from the origin with a slope of 2. At y=0, P=0. As y increases, P increases linearly. This implies that the firm is willing to supply more only at higher prices, reflecting the increasing cost of production.

Quantity (y) Price (P)
0 0
1 2
2 4
3 6

Conclusion

In conclusion, given the cost function C(y) = y² + 1, the derived inverse supply curve is P = 2y. This represents a positively sloped, linear supply curve, indicating a direct relationship between price and quantity supplied. The increasing marginal cost of production, as reflected in the cost function, drives the upward slope of the supply curve, demonstrating a fundamental principle of microeconomic theory. This analysis highlights how a firm’s cost structure directly influences its supply decisions in a competitive market.

Answer Length

This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.

Additional Resources

Key Definitions

Marginal Cost
The additional cost incurred by producing one more unit of a good or service. It is calculated as the change in total cost divided by the change in quantity.
Inverse Supply Curve
A representation of the supply curve where price is expressed as a function of quantity, rather than quantity as a function of price. It shows the minimum price suppliers are willing to accept for each quantity of a good or service.

Key Statistics

According to the National Sample Survey Office (NSSO) 78th round (2020-21), the average cost of production for agricultural commodities in India varies significantly across states and crops.

Source: NSSO Report No. 590, 2022

India's manufacturing sector contributed approximately 17.6% to the country's GDP in 2023-24.

Source: Ministry of Commerce and Industry, Government of India (as of knowledge cutoff)

Examples

Apple Inc. and iPhone Production

Apple Inc.'s production costs for iPhones directly influence the supply of iPhones. As component costs rise or production processes become more complex, Apple must increase the price to maintain profitability, leading to a shift in the supply curve.

Frequently Asked Questions

What happens to the supply curve if fixed costs increase?

An increase in fixed costs will shift the entire supply curve to the left, reducing the quantity supplied at each price level. This is because higher fixed costs increase the overall cost of production, making it less profitable to supply the same quantity at the same price.

Topics Covered

EconomyMicroeconomicsSupply and DemandMarket StructuresCost Analysis