Probability Calculator
Compute probability of two events: union (A or B), intersection (A and B), conditional probability, and odds.
P(A or B) — union
0.67
Breakdown
- P(A and B) — intersection
- 0.17
- P(not A)
- 0.50
- P(A | B) — conditional
- 0.50
- Odds of A (a:b)
- 1
Last updated:
FAQ
How do I combine probabilities?
For independent events, P(A and B) = P(A) × P(B) and P(A or B) = P(A) + P(B) − P(A)×P(B). For mutually exclusive events, 'and' is 0 and 'or' is simply the sum.
What is conditional probability?
P(A | B) is the chance of A given that B already happened. For independent events it equals P(A), because B tells you nothing about A.
What are the odds of flipping three heads in a row?
Each flip is independent: 0.5³ = 0.125 or 12.5%. Streaks feel unlikely but are statistically routine.
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