Conditional probability
Use a table, a Venn diagram and a tree to work out the probability of one event when you already know another, see why the order of "given" matters, and meet dependent events.
- UK: Year 10
- France: grade 10
- Germany: grade 11
- Iran: grade 11
- Afghanistan: grade 12
- Syria: grade 11
- Palestine: grade 9
- Russia: grade 10
Guide
This studio follows Afghan grade 12 chapter 8 (conditional probability: P(A given B) = P(A ∩ B) ÷ P(B), and the product rule) and the UK GCSE conditional probability from tables, Venn diagrams and trees.
"Given B" means we already know B happened, so only B is possible: B is the new whole. In a table, look only at the row or column of B.
Common mistakes worked on here: dividing by the grand total, mixing up P(A given B) with P(B given A), ignoring the condition, and treating events as unrelated when one changes the chance of the other.