2.3.2.1b - Costs

Calculate fixed costs, variable costs, total costs and average costs.

Use b - costs to connect the rule to the data and decision in the question.

This matters because b - costs determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b - costs to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: b - Costs is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.