Edexcel A-Level Economics B 9EB0
Scarcity, Choice and Potential Conflicts
Enterprise, Business and the Economy
Introducing the Market
The Role of Credit in the Economy
Market Failure and Government Intervention
Revenue, Costs, Profits and Cash
Business Growth and Competitive Advantage
Firms, Consumers and Elasticities of Demand
Productive Efficiency
Life in a Global Economy
The Economic Cycle
Introduction to Macroeconomic Policy
Globalisation
Economic Factors in Business Expansion
Impact of Globalisation on Global Companies
Impact of Globalisation on Local and National Economies
Global Labour Markets
Inequality and Re-Distribution
Competition and Market Power
Market Power and Market Failure
Market Failure Across the Economy
Macroeconomic Policies and Impact on Firms and Individuals
Risk and the Financial Sector
Competition and Market Power
Concentration ratios, interdependence and tacit agreement
- 3 things to know
- Papers 1 and 3
Overview
Concentration ratios and calculating them and market share, interpreting a high ratio and its weaknesses, interdependence in oligopoly, reluctance to cut or raise price, the kinked demand curve, price wars, tacit collusion and why regulators struggle to prove it, and the incentive to cheat on collusion.
What you need to know
Answer each one before you reveal it.
What does a concentration ratio measure?
Four firms hold 22%, 18%, 15% and 9% of a market. Calculate the four-firm concentration ratio.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What does a concentration ratio measure?
Model answer
A concentration ratio measures the combined market share held by the largest few firms in a market.
- 2
Four firms hold 22%, 18%, 15% and 9% of a market. Calculate the four-firm concentration ratio.
Model answer
The four-firm concentration ratio is 64%.
- 3
The three largest firms in a market hold 30%, 25% and 12% of sales. Calculate the three-firm concentration ratio and the share left to all other firms.
Model answer
The three-firm concentration ratio is 67% and the remaining firms share the other 33%.
- 4
What does a five-firm concentration ratio of 90% tell you about a market?
Model answer
The market is highly concentrated and is an oligopoly, because five firms make almost all of the sales.
- 5
State one weakness of the concentration ratio as a measure of competition.
Model answer
It counts market share but not the threat of entry, so a concentrated market that is easy to enter may still be competitive.
- 6
A firm sells £24 million in a market worth £160 million in total. Calculate its market share.
Model answer
Its market share is 15%.
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