Private sector/public sector firms

Private firms are owned by individuals or shareholders. Their main goal is to maximise profit:

$$\pi = TR - TC$$

where TR is total revenue and TC is total cost.

📈 Analogy: Think of a private firm as a lemonade stand run by a student. The student wants to earn the most money possible by selling lemonade at the best price and using the least amount of sugar and lemons.

💡 Key Decision: Set price where marginal revenue (MR) equals marginal cost (MC). If MR > MC, produce more; if MR < MC, produce less.

Public firms are owned by the government and aim to provide public goods or services that are not profitable but socially valuable.

📊 Analogy: Imagine a school library. The library is run by the school (government) and its purpose is to give students access to books, not to make money.

💡 Key Decision: Set price (often zero or very low) to maximise social welfare, not profit. The focus is on efficiency and equity.

1. Define private and public firms clearly.
2. Use the profit equation ($\pi = TR - TC$) when discussing private firms.
3. Explain the MR = MC rule with a simple example.
4. Highlight that public firms focus on social welfare rather than profit.
5. Use the comparison table to show key differences quickly.
6. Remember to mention that public firms may use subsidies or taxes to influence outcomes.
7. When answering “Why do public firms exist?” cite examples like utilities, public transport, and education.