Home

Conditional Probability Calculator

Online conditional probability: P(B|A)=P(AB)/P(A) given that A has occurred.

展开更多 ▾
P(B|A)=P(AB)/P(A)
Joint
Positive

📖 Tutorial | Conditional

1. Definition
The conditional probability P(B|A)=P(AB)/P(A) with P(A)>0.
2. Formula & Notation
P(AB),P(A)Joint, marginal
3. Properties & Laws
  • P(A)>0;
  • Multiplication P(AB)=P(A)P(B|A);
  • 0≤P(B|A)≤1;
  • For independent events =P(B).
4. Steps
  1. Enter P(AB),P(A);
  2. Click "Calculate";
  3. Or click "Load Example".
5. Worked Examples
Example: P(AB)=0.2,P(A)=0.5: P(B|A)=0.4.
6. Common Pitfalls
Divide by P(A);
Undefined at P(A)=0;
Condition restricts the sample space.

❓ FAQ | Conditional

Formula?
P(AB)/P(A).
P(A)=0?
Undefined.
Multiplication?
P(A)P(B|A).
Range?
0-1.
Example?
0.4.
Independent?
P(B).