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HomeQuestion 1FluencyCore
Original practice · Free Online RevisionSkill · union rule
If P(A)=0.62, P(B)=0.48 and P(A∩B)=0.30, find P(A∪B).
Statistics & ProbabilityCoreMaths revision
Probability: Conditional & Expected Value
Use event notation, conditional reasoning and expectation to analyse uncertainty.
Focus points
✓Use union, intersection and complements.
✓Apply conditional probability.
✓Calculate expected values.
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Practice setQuestion lineup
Try each question first, reveal a hint when you need one, then check the worked answer. Mark them done as you go — finish the set to claim your chips.
8 revision questions
Question 2FluencyCore
Original practice · Free Online RevisionSkill · complement
If P(A)=0.37, find P(Aᶜ).
Question 3FluencyCore
Original practice · Free Online RevisionSkill · conditional probability
If P(A∩B)=0.18 and P(B)=0.45, find P(A|B).
Question 4FluencyCore
Original practice · Free Online RevisionSkill · independence
Events A and B are independent with P(A)=0.4 and P(B)=0.7. Find P(A∩B).
Question 5FluencyCore
Original practice · Free Online RevisionSkill · expected value
A game pays $6 with probability 0.2, $2 with probability 0.5, and $0 otherwise. Find expected payout.
Question 6ApplicationCore
Original practice · Free Online RevisionSkill · without replacement
A box has 4 red and 6 blue balls. Two are drawn without replacement. Find P(both red).
Question 7ReasoningCore
Original practice · Free Online RevisionSkill · independence test
Given P(A)=0.5, P(B)=0.6 and P(A∩B)=0.3, are A and B independent?
Question 8ChallengeStretch
Original practice · Free Online RevisionSkill · Bayes reasoning
A disease test has sensitivity 0.95 and false-positive rate 0.04. If prevalence is 0.02, find P(disease | positive).