A firm's total cost is £3,400 when it produces 200 units and £3,418 when it produces 201 units. Calculate the marginal cost of the 201st unit.

Marginal cost is the change in total cost divided by the change in output, so it is £18 ÷ 1 = £18.

A firm sells 100 units at £50 each. To sell 110 units it must cut the price on all units to £48. What is marginal revenue per extra unit, and why is it below the price?

Revenue rises from £5,000 to £5,280, so marginal revenue is £280 ÷ 10 = £28 per unit; it is below the £48 price because the price cut also reduces the revenue earned on the units the firm was already selling.

A firm has fixed costs of £20,000 and average variable cost of £13 at an output of 2,500 units. Calculate average fixed cost, average total cost and total cost.

Average fixed cost is £20,000 ÷ 2,500 = £8, average total cost is £8 + £13 = £21, and total cost is 2,500 × £21 = £52,500.

Incomes rise by 5% and demand for a good falls by 2%. What is the income elasticity of demand, and what type of good is it?

YED is −2 ÷ 5 = −0.4, and because the figure is negative the good is inferior.

OCR A-Level Economics H460

Introduction to Microeconomics

Topic overview Economic and free goods, scarcity and positive and normative statements Economic agents and the factors of production Factor rewards, rationality and the objectives of economic agents Incentives and the functions of the price mechanism Market, planned and mixed economies and allocative and productive efficiency Opportunity cost, trade-offs and the production possibility curve Shifts of the production possibility curve and uses of opportunity cost

Microeconomics: The Role of Markets

Topic overview Specialisation, the division of labour and barter Money as a medium of exchange and the gains from specialisation Individual and market demand and joint, competitive and composite demand Movements along and shifts of the demand curve Individual and market supply and joint and competitive supply Movements along and shifts of the supply curve Consumer surplus and producer surplus How changes in price affect consumer and producer surplus Ceteris paribus and market equilibrium and disequilibrium Changes in demand and supply and their effects on related markets Price and income elasticity of demand and total revenue Cross elasticity, price elasticity of supply and the uses of elasticity Marginal utility, marginal cost and decisions at the margin Market failure and marginal social cost and benefit Positive and negative production and consumption externalities Information failure, asymmetric information and merit and demerit goods Merit and demerit good diagrams and correcting information failure Public, private and quasi-public goods The free rider problem and the provision of public goods Indirect taxes and subsidies to correct market failure State provision, price controls, buffer stocks and legislation Regulation, tradable pollution permits and government failure

Microeconomics: Business Objectives

Topic overview Profit maximisation and alternative business objectives Corporate social responsibility and the principal-agent problem Fixed, variable, average and marginal costs Diminishing returns and economies and diseconomies of scale Total, average and marginal revenue Profit, loss and normal and supernormal profit

Microeconomics: Market Structures

Topic overview Perfect competition in the short and long run and allocative efficiency Productive efficiency and perfect competition as a benchmark Monopoly characteristics, equilibrium and static efficiency Dynamic efficiency, price discrimination and natural monopoly Characteristics of monopolistic competition and its short run equilibrium Long run equilibrium and efficiency in monopolistic competition Characteristics of oligopoly, concentration ratios and the kinked demand curve Non-price competition, collusion and the pros and cons of oligopoly Characteristics of contestable markets, sunk costs and hit-and-run entry Efficiency, barriers and the limits of contestable markets

Microeconomics: The Labour Market

Topic overview Derived demand for labour and wage elasticity of demand Labour productivity, unit labour costs and marginal revenue product Supply of labour and wage elasticity of supply Short and long run labour supply, transfer earnings and economic rent Wage differentials, labour mobility and monopsony Trade unions, bilateral monopoly and the effects of monopsony Wage determination in a competitive labour market and labour market flexibility

Macroeconomics: Aggregate Demand and Aggregate Supply

Topic overview The circular flow of income, injections and leakages Methods of measuring national income Components of aggregate demand and their determinants The slope of the aggregate demand curve and what shifts it Consumption, income and the role of expectations Short run and long run aggregate supply curves Shifts in short run and long run aggregate supply Macroeconomic equilibrium and the effects of demand and supply shifts The national income multiplier and marginal propensities The accelerator, the economic cycle and output gaps

Macroeconomics: Economic Policy Objectives

Topic overview Economic growth, real and nominal GDP and GDP per capita Short and long run growth, the economic cycle and the effects of growth Economic structure, deindustrialisation and sustainable development Limitations of GDP and the Human Development Index Employment, unemployment rates and the objective of full employment Measures, types and costs of unemployment and the effects of full employment Inflation, deflation, real values and the CPI and RPI Calculating inflation with index numbers and its causes and consequences Balance of payments accounts and current account calculations Causes and consequences of current account imbalances Key trends in UK macroeconomic performance Comparing UK performance internationally and the limits of economic data Income and wealth, redistribution and absolute and relative poverty Lorenz curves, the Gini coefficient and the causes of poverty The natural rate of unemployment and Keynesian and neo-classical aggregate supply Short and long run Phillips Curves and their usefulness

Macroeconomics: Implementing Policy

Topic overview The government budget, types of tax and the budget balance National debt, cyclical and structural deficits and crowding out The Laffer curve, average and marginal tax rates and limits of fiscal policy Interest rates, the money supply and inflation targets Quantitative easing, the exchange rate and limits of monetary policy Privatisation, deregulation and subsidies as supply side policies Competition policy, infrastructure, education and tax and benefit reform Labour market flexibility, immigration control and limits of supply side policy Conflicts between macroeconomic policy objectives

Macroeconomics: The Global Context

Topic overview Patterns of international trade and global supply chains Advantages and disadvantages of international trade Exchange rate calculations and how exchange rates are determined Exchange rate changes, the Marshall-Lerner condition and exchange rate systems Globalisation, international competitiveness and comparative advantage Terms of trade and the impact of globalisation and emerging economies Protectionism and the effects of a tariff Quotas, trade creation, economic integration and the World Trade Organisation

Macroeconomics: The Financial Sector

Topic overview Functions of money, credit creation and narrow and broad money The quantity theory of money and interest rates in the money market Roles of the financial sector, saving and investment The Harrod-Domar model and microfinance Financial regulation and the functions of a central bank Monetary policy effectiveness, limits of regulation and the IMF

Quantitative Skills for Economics

Topic overview Ratios, percentages, averages, graphs, index numbers and real values Cost, revenue, profit and elasticity calculations

Themes in Economics: Synoptic Application

Topic overview Choosing models and judging data and assumptions in an unseen theme Efficiency, equity, sustainability and ethics in economic judgements

Quantitative Skills for Economics

Cost, revenue, profit and elasticity calculations

4 things to know
Components 01, 02 and 03

Overview

Recall questions on calculating total revenue, profit, average and marginal cost, marginal revenue, price, income and cross elasticity, price elasticity of supply, and price and volume changes.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Numbers

How are marginal cost and marginal revenue defined, and why is marginal revenue below price for a firm facing a downward-sloping demand curve?

Numbers

The price of a good rises from £8.00 to £8.80 and weekly sales fall from 40,000 to 37,000 units. Calculate the price elasticity of demand.

Numbers

A firm sells 4,000 units at £15 each and its total costs are £48,000. Calculate total revenue, profit and average cost.

Numbers

Weekly sales fall from 40,000 to 37,000 as price rises from £8.00 to £8.80. Calculate total revenue before and after; does that fit PED −0.75?

Questions from this subtopic

Each one with the model answer underneath.

1
A firm sells 4,000 units at £15 each and its total costs are £48,000. Calculate total revenue, profit and average cost.
Model answer
Total revenue is 4,000 × £15 = £60,000, profit is £60,000 − £48,000 = £12,000, and average cost is £48,000 ÷ 4,000 = £12 per unit.
2
A firm's total cost is £3,400 when it produces 200 units and £3,418 when it produces 201 units. Calculate the marginal cost of the 201st unit.
Model answer
Marginal cost is the change in total cost divided by the change in output, so it is £18 ÷ 1 = £18.
3
A firm sells 100 units at £50 each. To sell 110 units it must cut the price on all units to £48. What is marginal revenue per extra unit, and why is it below the price?
Model answer
Revenue rises from £5,000 to £5,280, so marginal revenue is £280 ÷ 10 = £28 per unit; it is below the £48 price because the price cut also reduces the revenue earned on the units the firm was already selling.
4
A firm has fixed costs of £20,000 and average variable cost of £13 at an output of 2,500 units. Calculate average fixed cost, average total cost and total cost.
Model answer
Average fixed cost is £20,000 ÷ 2,500 = £8, average total cost is £8 + £13 = £21, and total cost is 2,500 × £21 = £52,500.
5
The price of a good rises from £8.00 to £8.80 and weekly sales fall from 40,000 to 37,000 units. Calculate the price elasticity of demand.
Model answer
Price rises 10% and quantity falls 7.5%, so PED is −7.5 ÷ 10 = −0.75, meaning demand is price inelastic.
6
Incomes rise by 5% and demand for a good falls by 2%. What is the income elasticity of demand, and what type of good is it?
Model answer
YED is −2 ÷ 5 = −0.4, and because the figure is negative the good is inferior.

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