Define total, average and marginal revenue; derive AR and MR curves for a perfect competitor and a monopolist
Distinguish normal from supernormal profit; explain economic profit vs accounting profit
Apply the profit-maximisation rule (MR = MC) to find equilibrium output and price
Evaluate alternative business objectives beyond profit maximisation (Baumol, Marris, Simon)
Revenue Concepts
Total, Average & Marginal Revenue
Key Definitions
Total Revenue (TR) = Price × Quantity. Average Revenue (AR) = TR/Q = Price (the demand curve). Marginal Revenue (MR) = change in TR from selling one more unit. For a price-taker (perfect competitor): AR = MR = Price (horizontal demand curve). For a price-maker (monopolist): AR falls as Q rises (downward-sloping demand); MR falls twice as fast as AR and becomes negative at the point where TR is maximised.
PERFECT COMPETITOR'S REVENUE
Price fixed by market. TR rises linearly (P × Q). AR = MR = P (horizontal). Increasing Q doesn't require a price cut — the firm is a price-taker with perfectly elastic demand.
MONOPOLIST'S REVENUE
To sell more, price must fall. TR is an inverted U (maximised where MR=0). AR (demand curve) slopes down. MR lies below AR and is negative at Q beyond TR max. Key: MR = 0 at the peak of TR.
RELATIONSHIP BETWEEN PED AND MR
MR > 0 when PED > 1 (elastic — cutting price increases TR). MR < 0 when PED < 1 (inelastic — cutting price reduces TR). MR = 0 when PED = 1. Connects elasticity theory directly to revenue analysis.
Revenue Diagram
AR & MR Curves for a Monopolist
AR = Demand curve (downward-sloping)
MR (falls twice as steeply as AR)
MR = 0 where TR is maximised. MR hits x-axis at half the x-intercept of AR.
WHY MR < AR FOR MONOPOLIST
To sell one more unit, price must be cut for ALL units sold. Revenue gained from the new unit is partially offset by revenue lost on all previous units sold at the lower price. Hence MR < AR always for downward-sloping demand.
TR MAXIMISATION
TR is maximised where MR = 0 — not profit-maximising. Revenue maximisation gives higher output and lower price than profit maximisation (MR=MC). Important distinction for Baumol's theory.
PRACTICAL EXAMPLE
If demand curve is P = 100 – 2Q: TR = 100Q – 2Q². MR = 100 – 4Q (twice as steep). TR maximised at Q=25 (set MR=0: 100–4Q=0). Practice deriving MR from demand — this earns AQA marks.
Types of Profit
Normal vs Supernormal Profit
NORMAL PROFIT
The minimum return necessary to keep a firm in the industry — the opportunity cost of being here vs the next best use of resources. Included in economic costs. When TR = TC (including normal profit): economic profit = 0. Firm is making just enough to stay — no incentive to exit.
SUPERNORMAL PROFIT
TR > TC (including normal profit). Also called "abnormal profit" or "economic profit". Signals this industry is more profitable than alternatives → attracts new entrants in competitive markets. In perfect competition, supernormal profit is temporary. In monopoly, it can persist due to barriers to entry.
ECONOMIC vs ACCOUNTING PROFIT
Accounting profit = TR – explicit (monetary) costs. Economic profit = TR – explicit costs – implicit costs (opportunity costs). Economic profit ≤ accounting profit always. AQA: "normal profit" means zero economic profit — not zero accounting profit. Firms can make accounting profits while earning only normal profit.
SUBNORMAL PROFIT (LOSS)
TR < TC. Firm makes a loss. Short-run: will continue if TR > TVC (covers variable costs). Shutdown point: if TR < TVC, better to produce nothing. Long-run: exit industry if continued losses expected. Shutdown vs exit is a key AQA distinction.
Profit Maximisation
The MR = MC Rule
MC curve (U-shaped)
ATC curve
AR = Demand
MR
THE RULE
Profit is maximised where MR = MC. If MR > MC: producing one more unit adds more to revenue than to cost → increase output. If MR < MC: one more unit costs more than it earns → reduce output. At MR = MC: profit is at its maximum.
FINDING PRICE
After finding Q* (where MR=MC), read price from the demand (AR) curve above Q*. For a price-taker: P = MR = MC. For a price-maker (monopolist): P > MR = MC — price is above marginal cost, meaning allocative inefficiency.
PROOF WITH NUMBERS
If TR = 100Q – Q² and TC = Q³/3 – 2Q² + 30Q + 50: MR = 100 – 2Q; MC = Q² – 4Q + 30. Set MR = MC: 100 – 2Q = Q² – 4Q + 30 → Q² – 2Q – 70 = 0 → Q ≈ 9.4. Then read P from demand curve.
Alternative Objectives
Beyond Profit Maximisation
SALES/REVENUE MAXIMISATION (Baumol)
Managers may prefer to maximise sales revenue (set MR=0) rather than profit — higher salary, power, and market share follow from revenue growth. Gives higher output and lower price than profit maximisation. Conflicts with shareholder interests.
GROWTH MAXIMISATION (Marris)
Managers prefer firm growth (mergers, acquisitions) — job security, prestige, salary linked to firm size rather than profit. May sacrifice short-run profit for expansion. Can lead to overexpansion and diseconomies of scale.
SATISFICING (Simon)
Bounded rationality → firms don't optimise; they set minimum acceptable profit targets and satisfice. Once the target is met, managers pursue other goals (easy life, leisure). Relevant for large organisations with separated ownership and management.
STAKEHOLDER THEORIES
Firms may aim to satisfy a range of stakeholder interests — employees (fair wages), customers (value), environment (sustainability), community (CSR). B-corps, ESG investing, John Lewis Partnership. Evaluation: harder to define success; potential conflicts between groups; may trade off against profit.
Principal-Agent Problem
Ownership vs Control
Key Concept
The Principal-Agent Problem: when the principal (shareholders) delegates decision-making to an agent (managers), the agent may pursue their own interests rather than the principal's. Shareholders want profit maximisation; managers may prefer revenue maximisation, growth, or an easy life. This creates a divergence between ownership and control.
EXAMPLES
CEO bonus tied to share price → short-run decisions (share buybacks, cutting R&D) boost price at expense of long-run value. Bank traders (2008): upside was theirs (bonuses) but downside was shareholders' (losses). NHS consultants prescribing without bearing cost.
SOLUTIONS
Performance-related pay (profit-sharing, share options align manager and shareholder interests); monitoring (board of directors, non-executive directors, auditors); threat of hostile takeover (underperforming managers face job loss); market for corporate control.
EVALUATION
Incentive schemes may create perverse incentives (gaming metrics); monitoring is costly; even aligned agents may have different time horizons. Problem is endemic to large organisations — cannot be fully eliminated. Foundation of much corporate governance regulation.
Evaluation
Profit Maximisation vs Alternative Objectives
For profit maximisation
Profit maximisation is a precise, testable rule (MR=MC) that generates clear predictions for output and price
In competitive markets, firms that fail to maximise profit face elimination — suggests it is a long-run constraint even if not always pursued
Shareholders can discipline managers through takeovers, board oversight, and performance pay — aligning interests
Empirical evidence: firms in competitive industries do set prices close to MC (consistent with profit max), especially in the long run
Against profit maximisation
Separation of ownership and control (Berle & Means, 1932) — managers have different objectives from shareholders
Bounded rationality (Simon): firms lack full information to identify exactly where MR=MC — satisficing is more realistic
Short-termism: profit max may sacrifice long-run value (investment, R&D, reputation) for short-run returns
Managerial theories (Baumol, Marris) backed by evidence that executive pay correlates with firm size/revenue, not profit
Essay Tip: "The best evaluation acknowledges that profit maximisation is a useful benchmark but rarely describes actual firm behaviour. For AQA 25-mark essays, argue that the market structure matters: in competitive markets, profit max is a survival constraint; in monopoly, managers have more discretion to pursue alternative objectives. Always consider the principal-agent problem as the mechanism linking ownership and control."
Glossary
Key Terms
Total Revenue (TR)
Price × Quantity. For a price-taker, TR rises linearly. For a monopolist, TR is an inverted U, maximised where MR = 0.
Marginal Revenue (MR)
The additional revenue from selling one more unit. For a perfect competitor MR = Price. For a monopolist MR < AR, falls twice as fast as AR, and becomes negative beyond TR max.
Normal Profit
The minimum return to keep a firm in the industry — the opportunity cost of resources. Included in economic costs. Economic profit = 0 when only normal profit is earned.
Supernormal Profit
TR > TC (including normal profit). Also called abnormal or economic profit. Attracts entry in competitive markets but can persist in monopoly due to barriers to entry.
Profit Maximisation (MR=MC)
The output rule where profit is greatest: produce where MR = MC. If MR > MC increase output; if MR < MC reduce output. Price is read from the demand curve above Q*.
Principal-Agent Problem
When shareholders (principal) delegate to managers (agent), the agent may pursue their own goals (revenue, growth, quiet life) rather than the principal's goal (profit maximisation).
Question 1 of 8 · Revenue & Profit
For a price-taking firm in a perfectly competitive market, marginal revenue (MR) equals:
A
Half the market price, because splitting revenue between units
B
The market price (P), because selling one more unit adds exactly P to revenue
C
Average revenue divided by quantity sold
D
Zero, because the firm cannot influence price
Answer · Question 1
For a price-taking firm in a perfectly competitive market, marginal revenue (MR) equals:
A
Half the market price, because splitting revenue between units
B
The market price (P), because selling one more unit adds exactly P to revenue
C
Average revenue divided by quantity sold
D
Zero, because the firm cannot influence price
Correct: B. A price-taker faces a perfectly elastic (horizontal) demand curve at the market price. Every additional unit sold adds exactly that price to total revenue, so MR = AR = P. This is why for a perfect competitor, the profit-maximising condition MR = MC becomes P = MC — the basis of allocative efficiency.
Question 2 of 8 · Revenue & Profit
For a monopolist facing a downward-sloping demand curve, which statement about MR and AR is correct?
A
MR equals AR at all output levels, because both are derived from price
B
MR lies above AR because selling more raises revenue faster than average
C
MR lies below AR and falls twice as steeply for a linear demand curve
D
MR is constant while AR falls as quantity increases
Answer · Question 2
For a monopolist facing a downward-sloping demand curve, which statement about MR and AR is correct?
A
MR equals AR at all output levels, because both are derived from price
B
MR lies above AR because selling more raises revenue faster than average
C
MR lies below AR and falls twice as steeply for a linear demand curve
D
MR is constant while AR falls as quantity increases
Correct: C. To sell an extra unit, the monopolist must cut the price for all units sold. Revenue gained on the new unit is partially offset by the revenue lost on all previous units sold at the lower price — so MR < AR. For a linear demand curve P = a – bQ: TR = aQ – bQ², so MR = a – 2bQ (twice as steep as AR = a – bQ). MR hits the x-axis at half the quantity where AR hits it.
Question 3 of 8 · Revenue & Profit
In AQA Economics, a firm is said to be earning "normal profit" when:
A
Accounting profit is zero — total revenue equals total explicit costs
B
Economic profit is zero — total revenue covers all explicit and implicit (opportunity) costs
C
The firm earns above-average profits relative to comparable industries
D
Total revenue equals total variable costs, so fixed costs are covered
Answer · Question 3
In AQA Economics, a firm is said to be earning "normal profit" when:
A
Accounting profit is zero — total revenue equals total explicit costs
B
Economic profit is zero — total revenue covers all explicit and implicit (opportunity) costs
C
The firm earns above-average profits relative to comparable industries
D
Total revenue equals total variable costs, so fixed costs are covered
Correct: B. Normal profit is the opportunity cost of the entrepreneur's resources — the minimum return needed to keep the firm in the industry. It is included in economic costs. When TR exactly covers all costs including this opportunity cost, economic profit = 0. The firm is making just enough to stay — no incentive to enter or exit. This is why normal profit is compatible with positive accounting profit.
Question 4 of 8 · Revenue & Profit
A firm is producing at an output where MR > MC. To maximise profit, the firm should:
A
Reduce output, because profit is too high and attracting rivals
B
Increase output, because each additional unit adds more to revenue than to cost
C
Maintain current output — MR > MC is the profit-maximising condition
D
Reduce price, because high MR signals the firm is charging too much
Answer · Question 4
A firm is producing at an output where MR > MC. To maximise profit, the firm should:
A
Reduce output, because profit is too high and attracting rivals
B
Increase output, because each additional unit adds more to revenue than to cost
C
Maintain current output — MR > MC is the profit-maximising condition
D
Reduce price, because high MR signals the firm is charging too much
Correct: B. If MR > MC, each extra unit produced adds more to revenue than to cost — so profit rises with each additional unit. The firm should expand output until MR = MC (profit is maximised). Only at MR = MC is there no further gain from changing output. MR < MC signals over-production. MR = MC is the condition, not MR > MC.
Question 5 of 8 · Revenue & Profit
At the output where total revenue (TR) is maximised (MR = 0), a firm's profit is:
A
Also maximised — TR max and profit max are the same output
B
Zero, because TR just covers total costs at this output
C
Not maximised — profit max requires MR = MC, not MR = 0 (unless MC = 0)
D
Negative, because producing where MR = 0 always implies a loss
Answer · Question 5
At the output where total revenue (TR) is maximised (MR = 0), a firm's profit is:
A
Also maximised — TR max and profit max are the same output
B
Zero, because TR just covers total costs at this output
C
Not maximised — profit max requires MR = MC, not MR = 0 (unless MC = 0)
D
Negative, because producing where MR = 0 always implies a loss
Correct: C. TR is maximised where MR = 0. Profit = TR – TC, so profit is maximised where the gap between TR and TC is greatest — this occurs where MR = MC. Since MC is almost always positive (it costs something to produce each unit), MR=MC occurs at a lower output than MR=0. Revenue maximisation (Baumol's objective) therefore gives higher output and lower profit than profit maximisation.
Question 6 of 8 · Revenue & Profit
William Baumol's managerial theory of the firm argues that managers prefer to maximise:
A
Profit, because this maximises shareholder returns and manager bonuses
B
Sales revenue, because managerial salaries and status are often linked to firm size and revenue
C
Market share alone, even if this causes losses
D
Satisfactory profit, because managers prefer an easy life over optimisation
Answer · Question 6
William Baumol's managerial theory of the firm argues that managers prefer to maximise:
A
Profit, because this maximises shareholder returns and manager bonuses
B
Sales revenue, because managerial salaries and status are often linked to firm size and revenue
C
Market share alone, even if this causes losses
D
Satisfactory profit, because managers prefer an easy life over optimisation
Correct: B. Baumol's sales/revenue maximisation theory: managers maximise total revenue (set MR=0) subject to a minimum profit constraint (enough to keep shareholders from revolting). Managerial salaries, bonuses, prestige, and power are correlated with firm revenues rather than profits. This gives higher output and lower price than profit maximisation. Note: D describes Simon's satisficing theory, not Baumol's.
Question 7 of 8 · Revenue & Profit
The principal-agent problem in economics arises most directly because:
A
Shareholders always have better information than managers about firm performance
B
Managers (agents) may pursue their own objectives rather than those of shareholders (principals) when ownership and control are separated
C
Government regulators (the principal) fail to monitor firms (the agents) adequately
D
Firms always maximise profit, leaving no room for managerial discretion
Answer · Question 7
The principal-agent problem in economics arises most directly because:
A
Shareholders always have better information than managers about firm performance
B
Managers (agents) may pursue their own objectives rather than those of shareholders (principals) when ownership and control are separated
C
Government regulators (the principal) fail to monitor firms (the agents) adequately
D
Firms always maximise profit, leaving no room for managerial discretion
Correct: B. The principal-agent problem occurs when an agent (manager) makes decisions on behalf of a principal (shareholder) and the two parties have different objectives and information. Managers are better informed about the firm (information asymmetry) and may exploit this to pursue personal goals (revenue growth, status, risk aversion). A says the opposite of reality — it is managers who usually have more information, not shareholders.
Question 8 of 8 · Revenue & Profit
Supernormal profit can persist in the long run only if:
A
The firm produces at the lowest possible average cost
B
The government sets a minimum price above equilibrium
C
There are significant barriers to entry that prevent new firms from competing away profits
D
The firm sets MR = 0 rather than MR = MC
Answer · Question 8
Supernormal profit can persist in the long run only if:
A
The firm produces at the lowest possible average cost
B
The government sets a minimum price above equilibrium
C
There are significant barriers to entry that prevent new firms from competing away profits
D
The firm sets MR = 0 rather than MR = MC
Correct: C. In perfect competition, supernormal profit attracts new entrants → supply rises → price falls → long-run equilibrium restores normal profit only. For supernormal profit to persist in the long run, barriers to entry must prevent this competitive process — patents, economies of scale, brand loyalty, regulatory licences. This is why monopolists can sustain supernormal profit (abnormal profit) long-term, but perfectly competitive firms cannot.
Exam Technique
AQA Exam Tips: Revenue & Profit
DIAGRAMS
Always draw MC cutting MR from below at Q*. Then go vertically up to the demand (AR) curve to find P*. Shade the supernormal profit rectangle (between AR and ATC at Q*). Label all curves. The diagram earns marks even if your written analysis is weak.
DEFINITIONS
Always define your terms clearly. "Normal profit = the minimum return needed to keep the firm in the industry, equal to the opportunity cost of the entrepreneur's resources." Never write "normal profit = zero profit" — it means zero economic profit, not zero accounting profit.
ALGEBRA
If given a demand function P = a – bQ, MR = a – 2bQ (same intercept, twice the slope). TR = aQ – bQ². Set MR = MC and solve for Q*. Substitute Q* back into AR to find P*. This algebra is often in the data-response and earns specific marks.
EVALUATION
For 25-mark essays: argue that profit max is a useful model but real firms face principal-agent problems, bounded rationality, and stakeholder pressures. "It depends on market structure" — in competitive markets firms must profit-maximise to survive; in monopoly there is more managerial discretion.
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Lesson Complete
You've covered total, average and marginal revenue; AR and MR curves for perfect competitors and monopolists; normal vs supernormal profit; the MR=MC profit-maximisation rule; alternative business objectives (Baumol, Marris, Simon); and the principal-agent problem.
Practise AQA Theme 3 data-response questions that give a demand function and ask you to find Q* and P* using MR=MC. June 2019 Paper 3 Q1 is a classic. Also practise 25-mark essays on whether profit maximisation is a realistic assumption.
CONNECT TO OTHER TOPICS
Revenue & profit concepts underpin all market structures (perfect competition, monopolistic competition, oligopoly, monopoly). Link MR=MC to allocative efficiency (P=MC) and the welfare loss triangle. Connect principal-agent to corporate governance and market failure from information asymmetry.
REAL-WORLD EXAMPLES TO USE
Amazon pricing strategy (revenue maximisation in early years — sacrificing profit for growth, consistent with Marris). Apple vs Samsung (monopoly power, supernormal profit protected by patents). WeWork collapse (growth maximisation without profit constraint, principal-agent failure). Tesco 2014 accounting scandal (gaming profit metrics).