Questions: Market Equilibrium in Perfect Competition

Question 1

The equilibrium price in a perfectly competitive market is $10, but a particular firm's average total cost at its profit-maximizing output is $14. What will this firm do in the short run?

• A. Raise its price to $14 to cover its costs
• B. Lobby the government for a subsidy since it cannot survive at the market price
• C. Continue producing as a price-taker, accepting the $10 price, and sustain a loss of $4 per unit
• D. Increase output to spread fixed costs and reduce average total cost below $10

Answer: (C)

Competitive firms are price-takers — they cannot raise their price above the market equilibrium without losing all customers. In the short run, a firm producing where P = MC may still face losses if ATC exceeds price. It will continue operating as long as price covers average variable cost (since fixed costs are sunk), but it sustains an economic loss. This loss signals that resources should exit this industry — which drives the long-run adjustment toward zero economic profit. Option A is the key misconception: competitive firms do NOT set prices.

Question 2

A competitive market is in equilibrium. At the equilibrium quantity, the last unit produced costs $20 to produce, and consumers value it at $20. What does this tell us about the efficiency of the outcome?

• A. The market has failed, because the firm earns zero profit on the last unit
• B. The allocation is inefficient, because surplus could increase by producing more
• C. The allocation is allocatively efficient: the value of the last unit to consumers exactly equals the cost of producing it
• D. The allocation is efficient only if all firms are earning positive economic profits

Answer: (C)

Allocative efficiency means output is carried to the point where marginal benefit (the demand curve) equals marginal cost (the supply curve). The equilibrium is where these intersect, so the last unit produced is worth exactly as much to consumers as it costs to produce. Producing less would leave unrealized gains (consumers willing to pay more than the cost); producing more would mean the last unit costs more to produce than buyers value it. Total surplus — consumer plus producer — is maximized at this point. Whether any individual firm earns a profit is separate from whether the aggregate allocation is efficient.

Question 3

In a perfectly competitive market, individual firms have no influence over the equilibrium price — they are price-takers who accept the market price as given.

• T. True
• F. False

Answer: True

This is the defining feature of perfect competition: each firm is so small relative to the market that its individual output decision has a negligible effect on the total quantity supplied, and therefore on price. The market price is determined by the intersection of the market supply curve (aggregated across all firms) and the market demand curve. Any individual firm that tried to charge above the market price would lose all its customers to competitors offering identical products at the market price.

Question 4

A competitive market equilibrium guarantees that most firms in the market are earning at least normal (zero economic) profit.

• T. True
• F. False

Answer: False

Short-run competitive equilibrium guarantees allocative efficiency, not profitability. The equilibrium price is set by supply and demand, not by firms' average costs. At the short-run equilibrium, some firms may earn positive economic profits, some may break even, and some may sustain losses — depending on their individual cost structures. Profitability drives long-run entry and exit, which ultimately pushes toward zero economic profit in the long run, but short-run equilibrium carries no such guarantee.

Question 5

A perfectly competitive equilibrium is called 'allocatively efficient.' What exactly is efficient about it, and from whose perspective?

Model answer: Allocative efficiency means the total quantity produced is exactly the amount where the value of the last unit to consumers (the demand curve) equals the cost of producing it (the supply curve). No reallocation could increase the combined welfare of buyers and sellers — total consumer surplus plus producer surplus is maximized. It is efficient from society's aggregate perspective, not from any individual firm's perspective.

The efficiency is in the aggregate: no potential trade goes unrealized, and no resources are wasted producing units that cost more than they are worth. This contrasts with, say, a monopoly, which produces less than the efficient quantity and creates deadweight loss. It is not efficiency in the sense of being good for individual firms — a firm in competitive equilibrium may be losing money, and from its perspective, a higher price would be preferable. The social optimality result holds only under perfect competition's full assumptions (no externalities, no market power, complete information).