S1.3.2 - Sample space

Sample space.; Exclusive and Understanding and use of complementary events.; Conditional P(A′) = 1 − P(A), probability.; P(A ∪ B) = P(A) + P(B) − P(A ∩ B), P(A ∩ B) = P(A) P(B | A).

Use sample space to connect the rule to the data and decision in the question.

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

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

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