Welcome to the World of Firms and Decisions!
Ever wondered why a cup of coffee at a fancy cafe costs five times more than at a hawker centre? Or why some huge companies like Amazon can sell things so cheaply? It all boils down to Cost and Revenue. In this chapter, we’ll look behind the scenes of a business to see how they decide what to produce and how they try to make the most money possible. Don't worry if it seems like a lot of numbers at first—we'll break it down step-by-step!
1. Revenue: The Money Coming In
Before a firm can think about profit, it needs to sell things. The money a firm receives from selling its goods or services is called Revenue.
Key Revenue Concepts
Total Revenue (TR): This is the total "cash in the till."
Formula: \( TR = P \times Q \) (Price multiplied by Quantity sold).
Average Revenue (AR): This is the revenue per unit sold. In most cases, AR is simply the Price of the good.
Formula: \( AR = \frac{TR}{Q} = P \).
Marginal Revenue (MR): This is the extra money the firm gets from selling one more unit.
Formula: \( MR = \frac{\Delta TR}{\Delta Q} \).
Quick Review Box:
• TR = Big pile of money from all sales.
• AR = Price of one item.
• MR = The change in the pile of money when you sell just one more item.
Key Takeaway: Revenue is NOT profit. Revenue is just the total money collected before you pay any bills!
2. Costs: The Money Going Out
To make things, firms have to spend money on resources (land, labour, capital). We divide these costs based on time: the Short Run and the Long Run.
The Short Run vs. The Long Run
In Economics, these aren't specific amounts of time (like 6 months). Instead:
• Short Run: At least one factor of production is fixed (usually the size of the factory or the machinery).
• Long Run: All factors are variable. The firm can build a bigger factory or move to a new country.
Short Run Costs
Total Fixed Cost (TFC): Costs that do not change with output. Think of your Netflix subscription—you pay the same whether you watch 1 movie or 100. (e.g., Rent, insurance).
Total Variable Cost (TVC): Costs that change as you produce more. (e.g., Raw materials, electricity, part-time wages).
Total Cost (TC): Fixed Costs + Variable Costs. \( TC = TFC + TVC \).
Average Cost (AC): The cost per unit produced. \( AC = \frac{TC}{Q} \).
Marginal Cost (MC): The extra cost of producing one more unit.
Formula: \( MC = \frac{\Delta TC}{\Delta Q} \).
Analogy: The Popcorn Stand
Fixed Cost: The rent you pay for the stall space.
Variable Cost: The corn kernels and butter you buy for every bag sold.
If you sell zero bags, you still pay rent (Fixed), but you spend $0 on corn (Variable).
Key Takeaway: Marginal Cost (MC) is the most important "decision-making" cost. It tells the firm: "Is making this next item worth the extra expense?"
3. Profit Maximisation: The "Golden Rule"
Most firms aim to Maximise Profit. Profit is the difference between Total Revenue and Total Cost (\( Profit = TR - TC \)).
Where does Profit Maximisation happen?
A rational firm will continue to produce more as long as the extra revenue from the next unit (MR) is higher than the extra cost to make it (MC).
The Golden Rule: Profit is maximised at the output level where \( MR = MC \), provided that MC is rising.
Why MR = MC?
• If \( MR > MC \): The firm is making more money on the last unit than it cost to make. It should increase production to get more profit!
• If \( MC > MR \): The firm is losing money on that last unit. It should decrease production.
Did you know?
Firms don't always have perfect information. Sometimes they struggle to calculate their exact MR and MC in real-time, so they use "cost-plus pricing" (adding a percentage mark-up to their costs) as a rough guide.
Key Takeaway: Whenever you see a "Firms" question, your first thought should be "Where does \( MR = MC \)?". That is their "sweet spot."
4. Alternative Objectives of Firms
While profit is the main goal, some firms choose other paths:
1. Revenue Maximisation: Trying to get the TR as high as possible. This happens where \( MR = 0 \). (Often used to gain market share quickly).
2. Market Share Dominance: Sacrificing short-term profit to "kill off" competitors and become the biggest player (e.g., early years of Amazon or Grab).
3. Profit Satisficing: Managers do "just enough" to keep shareholders happy while pursuing their own goals (like work-life balance or personal prestige).
Common Mistake to Avoid: Don't confuse Revenue Maximisation with Profit Maximisation! Revenue Max ignores costs entirely, while Profit Max cares deeply about the gap between money in and money out.
5. Economies of Scale (EOS)
Why are big companies like IKEA or Sheng Siong often cheaper than small shops? It's because of Internal Economies of Scale.
Internal Economies of Scale
As a firm increases its scale of production (gets bigger), its Average Cost falls. This happens because of:
• Technical EOS: Using bigger, more efficient machines.
• Marketing EOS: Spreading the cost of one TV ad over millions of units sold.
• Managerial EOS: Hiring specialist accountants or lawyers who are more efficient.
External Economies of Scale
These occur when the entire industry grows, lowering costs for all firms in that industry.
Example: If many tech firms move to one area (like Silicon Valley or One-North in Singapore), the government might build better roads or training centres nearby, benefiting everyone.
Diseconomies of Scale
Can a firm be too big? Yes! If a firm grows too large, Average Costs might start to rise. This is often due to communication problems, "red tape," or low worker morale in a massive, impersonal company.
Memory Aid: "EOS is Boss"
• Internal EOS = "I" am getting bigger and more efficient.
• External EOS = "Everyone" in the industry is benefiting from the surroundings.
• Diseconomies = The "Disaster" of being too big to manage.
Key Takeaway: Firms want to achieve EOS to lower their unit costs, which allows them to either lower prices for customers or keep higher profits for themselves.
6. Summary Checklist for Students
Before moving on, make sure you can:
• Explain the difference between Total, Average, and Marginal concepts.
• Identify the profit-maximising condition (\( MR = MC \)).
• Distinguish between Fixed and Variable costs in the Short Run.
• Explain how getting bigger can lower costs (Internal EOS) or raise them (Diseconomies).
Don't worry if the curves look confusing at first. Just remember: Revenue is the prize, Cost is the price, and Profit is the difference!