Science & Statistics
Probability Calculator
Calculate combined probabilities for independent, dependent, and mutually exclusive events.
How this calculator works
For independent events: P(A∩B) = P(A) x P(B) and P(A∪B) = P(A) + P(B) - P(A∩B). For mutually exclusive: P(A∩B) = 0 and P(A∪B) = P(A) + P(B). For dependent events: P(A∩B) = P(A) x P(B|A). Also shows complement probabilities.
Enter as decimal (0.3 = 30%) or will be converted
Probability of B given A has occurred (only needed for dependent events)
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FAQ
Frequently asked questions
What does independent events mean?
Two events are independent if the outcome of one does not affect the other. For example, flipping a coin and rolling a die are independent. P(A and B) = P(A) x P(B) for independent events.
What does mutually exclusive mean?
Mutually exclusive events cannot happen at the same time. For example, a coin landing heads and tails on the same flip. P(A and B) = 0 and P(A or B) = P(A) + P(B) for mutually exclusive events.
How do I calculate P(A or B)?
The addition rule: P(A or B) = P(A) + P(B) - P(A and B). For mutually exclusive events, this simplifies to P(A) + P(B) since P(A and B) = 0.
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