Problem-Solving and Data AnalysisVery hardProbability of at least one of two events
Problem-Solving and Data Analysis practice question
For two events A and B, the probability of A is 0.5, the probability of B is 0.4, and the probability that both A and B occur is 0.2. What is the probability that A or B or both occur?
Answer: 0.7 or .7 or 7/10
P(A or B) = P(A) + P(B) − P(A and B) = 0.5 + 0.4 − 0.2 = 0.7.
Common wrong answers
- If you answered 0.9
- 0.9 adds the probabilities without removing the overlap.
- If you answered 0.2
- 0.2 is the probability of both.
- If you answered 0.3
- 0.3 is the probability of neither.
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