Why one project needs four fields
Each field answers one question.
- Marketing: Who will buy, at what price, and how many?
- Management: Who does which task, and can the team make enough?
- Accounting: How much money comes in and goes out, and what is left?
- Information: What do the numbers say, and were our guesses right?
A stall with great marketing but too few helpers loses sales. A stall with many helpers but no buyers loses money. All four must fit.
Marketing and management: demand and capacity
Marketing estimates demand. Our model: demand = 90 − 2 × price. At price 25, demand is 40 cups.
Management sets capacity: how many cups the team can make. Each helper makes 25. With 2 helpers capacity is 50.
Cups sold = the smaller of demand and capacity. If capacity is lower than demand, extra buyers go away. If demand is lower, extra capacity is wasted.
Accounting: counting the money
Revenue = price × cups sold = 25 × 40 = 1000.
Costs: ingredients 10 per cup (400), stall fee 200 (fixed), helper pay 50 each (100).
Profit = revenue − all costs = 1000 − 700 = 300.
Notice that more helpers cost money. A helper is worth adding only if the extra cups sold bring more profit than 50.
Information: forecast versus real, then decide
Write the forecast and the real numbers side by side. Forecast: 40 cups, profit 300. Real: 36 cups, profit 36 × 15 − 300 = 240. The gap is 60.
Ask why: was the survey too small? Was the weather hot or cold? Use the answer to improve the next plan. This is how the four fields join into a loop.
Try it
Pick a small project, such as selling old books. Write one line for each field: who buys and at what price, who does what, the money in and out, and which numbers you will check. Then play with the sliders in the 3D to see how price and helpers together change profit.
Key formulas and definitions
- Demand = 90 − 2 × price (model)
- Capacity = 25 × helpers
- Cups sold = smaller of demand and capacity
- Revenue = price × cups sold
- Profit = revenue − 10 × cups − 200 − 50 × helpers
Worked examples
1. Price 25, 2 helpers. How many cups are sold?
Demand = 90 − 50 = 40. Capacity = 2 × 25 = 50. Sold = smaller = 40.
2. Find the profit for price 25 and 2 helpers.
Revenue = 40 × 25 = 1000. Costs = 400 + 200 + 100 = 700. Profit = 300.
3. Same price but only 1 helper. What is the profit?
Capacity = 25, demand = 40, so sold = 25. Revenue = 625. Costs = 250 + 200 + 50 = 500. Profit = 125. One helper is too few.
4. The forecast was 40 cups but 36 sold. What is the real profit?
Profit = 36 × (25 − 10) − 200 − 100 = 540 − 300 = 240.
Common mistakes
- Thinking each field works alone. A change in one changes the others.
- Counting sales above what the team can make. Sold = smaller of demand and capacity.
- Forgetting helper pay and fixed fees when finding profit.
- Never comparing forecast with real results. Always check the gap.