Probability Calculator
Combined probabilities of two independent events.
- P(A or B)
- 0.7
- P(not A)
- 0.5
- P(not B)
- 0.6
- P(exactly one)
- 0.5
- P(neither)
- 0.3
How this calculator works
Enter each probability as a number between 0 and 1. For independent events, the probability of both is the product of the two.
Formula
P(A ∩ B) = P(A)·P(B); P(A ∪ B) = P(A) + P(B) − P(A)·P(B)
Example
With P(A) = 0.5 and P(B) = 0.4, both happen with probability 0.2 and at least one with 0.7.
When to use it
- Games of chance
- Reliability of two-part systems
- Statistics coursework
Frequently asked questions
What are independent events?
Events where one happening does not change the chance of the other, such as two separate coin flips.
How do I convert odds to probability?
For odds of a to b in favor, the probability is a ÷ (a + b). Odds of 1 to 3 give a probability of 0.25.
Learn more
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