S1.3.1 - Elementary probability

Elementary probability.

Use elementary probability to connect the rule to the data and decision in the question.

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

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

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