The events A and B are such that P(A)=320\displaystyle P(A) = \frac{3}{20}P(A)=203, P(A∩B)=120\displaystyle P(A \cap B) = \frac{1}{20}P(A∩B)=201, P(A∣B)=514\displaystyle P(A|B) = \frac{5}{14}P(A∣B)=145.
Find P(B)P(B)P(B)
Find P(A∪B)P(A \cup B)P(A∪B)
Find P(B∣A′)P(B|A')P(B∣A′)
Hence find P(A′∣B′)P(A'|B')P(A′∣B′)
330 exam-style questions on Edexcel A Level Maths Conditional Probability, covering 2.1 Set Notation, 2.2 Conditional Probability, 2.3 Conditional Probabilities in Venn Diagrams, 2.4 Probability Formulae, and 2.5 Tree Diagrams. Each one has a worked solution and a mark scheme showing where the marks go.