Unit 3: Market Structures

Answer: A — The correct answer is A. In monopolistic competition, firms produce differentiated products (through branding, quality differences, location, or other features), which makes their products imperfect substitutes for competitors' products. This differentiation gives each firm some price-setting power, resulting in a downward-sloping demand curve. Customers are somewhat loyal to the firm's specific product, so the firm can raise prices without losing all customers. B is incorrect because monopolistically competitive firms are typically small and cannot influence overall market price—only their own product's price. C is incorrect because monopolistic competition is characterized by LOW barriers to entry, not high ones; this is what keeps long-run profits near zero. D is incorrect because cartels are illegal and represent collusive behavior, which is fundamentally different from monopolistic competition, where firms act independently.

Answer: C — The correct answer is A. In perfect competition, long-run equilibrium occurs where Price = Average Total Cost = Marginal Cost. At this point, firms earn zero economic profit, meaning total revenue exactly equals total economic costs (including both explicit costs like wages and materials, AND implicit costs like the owner's opportunity cost of capital). This is called 'normal profit' and is sufficient to keep firms in the market. Option B is incorrect because product differentiation is a characteristic of monopolistic competition, not perfect competition, where products are homogeneous. Option C is incorrect because government subsidies are not a feature of perfectly competitive markets and would distort the natural equilibrium. Option D is incorrect because firms cannot simply reduce output to charge higher prices in perfect competition—they are price takers and must accept the market price, and reducing output would not change the market-determined price.

Answer: A — This scenario describes monopolistic competition because there are many firms, low barriers to entry, and the firms produce differentiated products. This gives them some power to set their prices. The correct answer is D. Answer A is incorrect because in perfect competition, firms produce a homogeneous product and have no power to set prices. Answer B is incorrect because a monopoly has only one firm and high barriers to entry. Answer C is incorrect because it describes a market with homogeneous products, not differentiated products.

Answer: A — This question tests understanding of oligopolistic interdependence and the outcome of price wars. The correct answer is A because when all oligopolists match a price cut, the relative price positions remain unchanged (each firm still holds 25% market share), so individual firms don't gain the market share advantage they initially sought. However, the lower industry price causes the quantity demanded for the entire market to increase due to the law of demand. Since total quantity demanded rises but each firm's market share stays constant, each firm sells more units. However, because price has fallen by 10% and quantity hasn't increased by more than 10% (due to the relatively inelastic demand for many oligopoly products), total industry revenue declines (Price × Quantity decreases). Option B is incorrect because when all firms match the price cut, no individual firm gains relative market share—they all remain at 25% each. Option C is wrong because a 10% price reduction by all competitors is not predatory pricing; it's rational competitive response, and consumer surplus actually increases due to lower prices. Option D is incorrect because oligopolies don't move to perfect competition simply through price matching—they maintain market power and barriers to entry remain intact. The firms will still earn positive economic profit in the long run due to differentiation and barriers to entry characteristic of oligopolies.

Answer: B — The correct answer is B. In monopolistic competition, when firms earn short-run economic profits, new firms are attracted to enter the market. As entry occurs, each existing firm's demand curve shifts leftward (its market share decreases), reducing its profit. Long-run equilibrium occurs where economic profit is zero, but—and this is the key distinction from perfect competition—the firm still faces a downward-sloping demand curve due to product differentiation. Therefore, at the long-run equilibrium quantity, price exceeds marginal cost (P > MC), creating allocative inefficiency. This is the fundamental difference from perfect competition, where P = MC in long-run equilibrium. Why the other options are incorrect: - A) Incorrectly suggests that the long-run equilibrium condition is P = MC, which is only true in perfect competition. In monopolistic competition, the downward-sloping demand curve means P > MC even in long-run equilibrium. - C) Misunderstands the nature of monopolistic competition. While product differentiation exists, it does not create significant barriers to entry. Competitors can still enter with their own differentiated products, which is why economic profits are eliminated in the long run. - D) Contradicts basic economic logic. New entry increases competition and reduces demand for existing firms' products, thereby reducing—not increasing—their profit.