This topic explains how a firm turns inputs into output, and what that output costs. Table questions in SPM Economics ask you to find a figure and then explain it.
This cluster is part of SPM Economics. It has four skills, in the order that works best.
What does this cluster cover?
- Distinguishing short run and long run decides which inputs a firm can change.
- Calculating total, average and marginal quantities separates three figures that look alike.
- Explaining productivity links output to the inputs used to make it.
- Interpreting revenue, cost and profit tables finds break-even and the most profitable output.
For a deeper drill on one supplied table, continue to cost and productivity from a supplied table.
One short example: a fictional bakery
A bakery has one oven. With one baker it makes 20 trays a day, and with two bakers it makes 44 trays.
The second baker adds 24 trays, which is more than the first baker added, because the two can share jobs. A third baker adds only 10 trays, because three people now queue for one oven.
This one table shows the main ideas of the cluster. The oven is fixed, so this is the short run. The changing additions (20, 24, 10) are marginal quantities, and the total and average come from the same numbers.
| Bakers | Total trays | Extra from last baker | Trays per baker |
|---|---|---|---|
| 1 | 20 | 20 | 20 |
| 2 | 44 | 24 | 22 |
| 3 | 54 | 10 | 18 |
How do the parts connect?
Short run versus long run tells you what can change. Total, average and marginal figures describe what happens when it does. Productivity asks whether the output per worker improved, and profit tables add prices and costs.
If the first lesson is solid, the others read as steps in one story. If it is not, the words “fixed” and “variable” stay vague in every table.
Who should start where?
- Unsure what “short run” means: start with short run and long run.
- Mixing up average and marginal: start with total, average and marginal quantities.
- Write “output rose so productivity rose”: start with explaining productivity.
- Can calculate but cannot decide the best output: start with revenue, cost and profit tables.
Test yourself with the production and costs practice set. For a teacher to check your table work with you, see online one-to-one Economics tuition.