Theory of Costs and Revenue: JAMB Economics Questions, Answers & Notes

What Theory of Costs and Revenue covers in the JAMB Economics syllabus

Costs are fixed (unchanged by output, e.g. rent — also called overheads), variable (change with output, e.g. raw materials) or their sum, total cost (TC = TFC + TVC). Average cost = TC ÷ quantity, and marginal cost is the extra cost of one more unit; average fixed cost falls as output rises. Revenue: total revenue = price × quantity, average revenue = price per unit, and marginal revenue is the extra revenue from one more unit. Profit = total revenue − total cost; a firm breaks even when TR = TC and makes a loss when TC > TR. A firm maximises profit where marginal cost equals marginal revenue.

For Theory of Costs and Revenue, JAMB expects you to be able to:

• Distinguish fixed, variable, total, average and marginal cost
• Define total, average and marginal revenue and calculate profit
• Explain break-even and the profit-maximising rule (MC = MR)

Key facts & revision notes: Theory of Costs and Revenue

These are the recurring points our Theory of Costs and Revenue questions test — revise them until each feels automatic, then practise the questions above to lock them in.

• Fixed costs stay the same regardless of output (e.g.
• Variable costs change with output (e.g.
• raw materials, wages of casual labour).
• Total cost (TC) = total fixed cost (TFC) + total variable cost (TVC).
• Average cost (AC) = total cost ÷ quantity produced.
• Marginal cost (MC) is the additional cost of producing one more unit.
• Total revenue (TR) = price × quantity sold.
• Profit = total revenue − total cost.
• Profit = TR − TC = 5,000 − 3,000 = ₦2,000.
• At break-even, total revenue equals total cost (profit is zero).
• AC = TC ÷ quantity = 20,000 ÷ 100 = ₦200.
• Rent does not change with output, so it is a fixed cost.
• Raw material costs rise with output, so they are variable costs.
• Average revenue (AR) = total revenue ÷ quantity = price per unit.
• Marginal revenue = change in total revenue = 450 − 400 = ₦50.
• Average fixed cost falls as output rises, since the fixed cost is spread over more units.
• Profit is maximised where marginal cost = marginal revenue.
• TC = TFC + TVC = 1,000 + 4,000 = ₦5,000.
• Overheads are fixed costs that must be paid regardless of output.
• Short-run cost curves reflect the law of diminishing returns as output changes.
• When total cost exceeds total revenue, the firm makes a loss.
• Costs that don't change with output are fixed costs.
• Costs varying with output are variable costs.
• Total cost = fixed cost + variable cost.

Worked examples

Three Theory of Costs and Revenue questions with the answer and a short explanation, so you can see how the topic is set before you practise the full set.

How Theory of Costs and Revenue is tested in JAMB Economics

Our Theory of Costs and Revenue bank holds 40 questions (4 easy, 23 medium, 13 hard). JAMB Economics typically returns to Theory of Costs and Revenue year after year, so steady practice on this topic is high-value revision. Questions are multiple-choice with four options, and at UTME pace you get roughly 40 seconds each — which is why timed practice matters.

How to answer Theory of Costs and Revenue questions

Work the stem first and predict the answer before you look at the options; then eliminate the ones that contradict the key facts above. Watch for “which is not…”, “all of the above” and “except” style stems, which are where rushed candidates lose easy marks on Theory of Costs and Revenue. If a calculation or a precise definition is involved, work it from first principles rather than guessing from a half-remembered rule. When two options look right, re-read the stem for the qualifier that separates them — JAMB rarely repeats an option by accident. If you are still unsure, eliminate the two weakest choices to lift your odds, flag the question, and move on; never burn a full minute on one Economics item when the exam gives you about forty seconds each. Then come back to flagged questions with whatever time remains. The single most reliable way to get faster at Theory of Costs and Revenue is repeated timed practice, so use the button above until the recurring patterns feel automatic.

Common mistakes to avoid in Theory of Costs and Revenue

The errors that cost marks on Theory of Costs and Revenue are usually careless rather than conceptual: misreading a negative stem, confusing two similar terms, or rushing a definition you actually know. Candidates also over-rely on “expo” and last-minute cramming instead of understanding the topic — which fails the moment JAMB rephrases a familiar idea. Treat every option as a claim to be checked against the facts above, keep your working tidy for any calculation, and don’t change a considered answer on a hunch. Above all, revise Theory of Costs and Revenue actively by answering questions, not just by re-reading notes — recall under time is what the exam rewards.

Frequently asked questions

Is Theory of Costs and Revenue part of the JAMB Economics syllabus?

Yes. Theory of Costs and Revenue is a recognised topic in the JAMB Economics syllabus, covering distinguish fixed, variable, total, average and marginal cost. You should be able to recall its key facts and apply them to multiple-choice questions.

How many Theory of Costs and Revenue questions can I practise on Belmadeng?

There are 40 original, JAMB-standard Theory of Costs and Revenue questions in our free bank, each with the correct answer and a worked explanation. You can practise them untimed or as a timed test.

What are the most important points to know about Theory of Costs and Revenue?

Costs are fixed (unchanged by output, e.g. rent — also called overheads), variable (change with output, e.g. raw materials) or their sum, total cost (TC = TFC + TVC). Average cost = TC ÷ quantity, and marginal cost is the extra cost of one more unit; average fixed cost falls as output rises. Revenue…

How do I answer Theory of Costs and Revenue questions quickly in JAMB?

Read the stem carefully, eliminate clearly wrong options, and match the remaining choices to the key facts for Theory of Costs and Revenue. Practising timed Theory of Costs and Revenue questions builds the speed you need for UTME's pace of about 40 seconds per question.

Are these JAMB Economics Theory of Costs and Revenue questions past questions or original?

They are original questions written to JAMB (UTME) standard and mapped to the official syllabus — not reproduced past papers. This keeps them legal to use freely while closely mirroring how the real exam tests the topic.

Where can I practise Theory of Costs and Revenue questions free without signing up?

Right here — tap “Start Theory of Costs and Revenue practice” on this page to begin instantly. Belmadeng's CBT practice is completely free and needs no sign-up, download or subscription.

About these questions: original, JAMB-standard items written from the official UTME Economics syllabus (last reviewed 2026-09-18). Belmadeng is an independent study platform and is not affiliated with JAMB. Spotted an error? Use the report link.