Monopolistic Competition Practice Questions

8 representative multiple-choice questions on monopolistic competition for AP Microeconomics, drawn from our 15-question bank for this module. Work through each one, then open “Show answer” for the correct choice and an explanation. For scored, timed practice across the full bank, take a full practice test.

1. 1. In the long run, a monopolistically competitive firm earns zero economic profit because:

   • A. The government regulates prices to equal average total cost
   • B. Free entry and exit shift the firm's demand curve until P = ATC
   • C. Firms collude to set prices equal to marginal cost
   • D. Consumers become indifferent between products over time
   Show answer

   Correct answer: B. Free entry and exit shift the firm's demand curve until P = ATC

   Free entry does the work. New firms enter whenever profit exists, stealing customers from incumbents. Each firm's demand curve slides left until it's tangent to ATC, so P = ATC and profit is gone. No government regulation or collusion involved. (D) is wrong because products remain differentiated even in the long run; consumers still prefer one brand over another.

2. 2. Excess capacity in monopolistic competition means the firm:

   • A. Produces more output than the socially optimal level
   • B. Operates on the upward-sloping portion of its ATC curve
   • C. Produces less than the quantity that minimizes average total cost
   • D. Has marginal cost equal to average total cost at its chosen output
   Show answer

   Correct answer: C. Produces less than the quantity that minimizes average total cost

   Look at the ATC curve on the graph. The firm operates on the downward-sloping portion, to the left of the minimum point. It could lower average cost by producing more, but MR = MC doesn't call for that higher output level. (B) places the firm on the wrong side of the curve. (D) describes the minimum-ATC point itself, which is precisely where the firm does not produce.

3. 3. A monopolistically competitive firm maximizes profit by producing where:

   • A. Price equals marginal cost
   • B. Price equals average total cost
   • C. Marginal revenue equals marginal cost
   • D. Marginal revenue equals average total cost
   Show answer

   Correct answer: C. Marginal revenue equals marginal cost

   MR = MC. Same profit-maximization rule as any firm with market power: find that intersection on the graph, then read up to the demand curve for price. (A) is the perfect competition result. (B) is the zero-profit condition in long-run equilibrium, a result, not a decision rule. (D) has no economic significance in any market structure.

4. 4. In long-run equilibrium, the demand curve of a monopolistically competitive firm is tangent to:

   • A. The marginal cost curve
   • B. The marginal revenue curve
   • C. The average total cost curve
   • D. The average variable cost curve
   Show answer

   Correct answer: C. The average total cost curve

   Tangent to ATC. That single tangency point is where P = ATC and economic profit hits zero. If demand intersected ATC at two points, the firm could earn profit between them, so it must be tangency, not intersection. (A) would mean P = MC, which is the perfect competition outcome. (D) has no role in the long-run equilibrium condition.

5. 5. A monopolistically competitive firm advertises heavily to differentiate its product. If successful, this advertising will:

   • A. Make the firm's demand curve more elastic (flatter)
   • B. Shift the firm's demand curve to the right and make it less elastic
   • C. Eliminate excess capacity by moving production to minimum ATC
   • D. Convert the market structure to perfect competition
   Show answer

   Correct answer: B. Shift the firm's demand curve to the right and make it less elastic

   Successful advertising builds brand loyalty. More customers arrive (demand shifts right) and existing customers become less price-sensitive (demand steepens, becoming less elastic). Short-run profit rises temporarily. (A) gets the elasticity direction wrong because loyalty reduces sensitivity to price, it doesn't increase it. (C) misunderstands the model; excess capacity is structural and advertising doesn't eliminate it. (D) is the opposite of what happens because stronger differentiation moves further from perfect competition.

6. 6. Excess capacity in monopolistic competition exists because in long-run equilibrium, the firm produces:

   • A. On the upward-sloping portion of ATC, beyond minimum ATC
   • B. At the minimum point of the ATC curve where P = MC
   • C. On the downward-sloping portion of ATC, to the left of minimum ATC
   • D. Where marginal cost intersects the demand curve
   Show answer

   Correct answer: C. On the downward-sloping portion of ATC, to the left of minimum ATC

   The tangency between demand and ATC occurs on the downward-sloping portion, to the left of minimum ATC. The firm could theoretically lower average cost by producing more, but pushing output higher would drop price below ATC and generate losses. That gap between actual output and minimum-ATC output is the excess capacity you can see on the graph. (A) places the firm on the wrong side. (B) describes perfect competition's long-run equilibrium.

7. 7. A monopolistically competitive firm earns zero economic profit in long-run equilibrium. A new study reveals that the firm's product causes health problems, reducing consumer demand. In the short run, the firm will:

   • A. Continue earning zero profit because entry and exit maintain equilibrium
   • B. Earn economic losses as demand shifts left and P falls below ATC
   • C. Raise its price to compensate for lost sales volume
   • D. Switch to producing a different product immediately
   Show answer

   Correct answer: B. Earn economic losses as demand shifts left and P falls below ATC

   Starting from zero profit, any leftward demand shift drops the demand curve entirely below ATC at the profit-maximizing output. The firm still sets MR = MC (that's rational even when losing money), but price now falls below ATC, generating losses. (A) confuses short run with long run; exit takes time, so losses persist until firms actually leave. (C) is irrational; with fewer customers, raising price would drive quantity demanded even lower.

8. 8. Industry-wide advertising in a monopolistically competitive market increases total demand for the product category but also increases each firm's costs. The most likely long-run effect is:

   • A. All firms earn persistent economic profit from the demand increase
   • B. Economic profit remains zero because entry offsets demand gains, while higher costs shift ATC upward
   • C. Firms exit the market because advertising costs exceed the revenue gains
   • D. The market converts to an oligopoly as only large firms can afford advertising
   Show answer

   Correct answer: B. Economic profit remains zero because entry offsets demand gains, while higher costs shift ATC upward

   Free entry neutralizes any profit boost. Even if advertising grows total demand, profit attracts entrants who split the market. Long-run equilibrium returns to zero economic profit, but now with a higher ATC curve because of advertising costs, so each firm charges a higher price to cover those costs while still earning zero profit. (A) ignores the free entry condition entirely. (C) is too gloomy; if advertising were unprofitable, rational firms would stop doing it and the market would adjust.