Probability measures how likely an event is to occur, expressed as a number between 0 (impossible) and 1 (certain). P(A) = favorable outcomes / total outcomes. Understanding probability is crucial in statistics, games, risk assessment, and decision-making.
How to Use
Calculate probabilities:
- Single event: Favorable / Total outcomes
- Combined: AND (multiply) or OR (add minus overlap)
- Complement: P(not A) = 1 - P(A)
Key Formulas
- P(A) = favorable / total
- P(A AND B) = P(A) × P(B) (independent)
- P(A OR B) = P(A) + P(B) - P(A AND B)
- P(not A) = 1 - P(A)
Odds vs Probability
Odds 3:1 means 3 favorable vs 1 unfavorable = probability 3/4 = 75%. Probability 0.8 = odds 4:1 (4 favorable for every 1 unfavorable).
Step-by-Step Instructions
- 1Enter favorable outcomes.
- 2Enter total outcomes.
- 3View probability, percentage, and odds.
- 4Check complement probability.
- 5Try combined event calculations.