🎯 Probability Calculator
Calculate combinations, permutations, and conditional probability. Perfect for statistics, combinatorics, and probability theory problems.
Choose a mode and click calculate
Probability Formulas
| Formula | Expression | Use Case |
|---|---|---|
| Combinations | C(n,r) = n! / (r! × (n-r)!) | Lotto numbers, team selection |
| Permutations | P(n,r) = n! / (n-r)! | Passwords, seating arrangements |
| Conditional | P(A|B) = P(A∩B) / P(B) | Medical tests, Bayesian inference |
Frequently Asked Questions
What is the difference between combinations and permutations?
Combinations (C(n,r)) count selections where order doesn't matter. Permutations (P(n,r)) count arrangements where order matters. P(n,r) = C(n,r) × r!
How do you calculate conditional probability?
P(A|B) = P(A ∩ B) / P(B). It measures the probability of event A given that event B has already occurred.