Negative Binomial Trials
Find the chance the rth success occurs on trial n.
Your numbers
Probability
Use consistent units. The result follows the assumptions you enter.
Scenario comparison
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Formula
P(T=n)=C(n−1,r−1)pʳ(1−p)ⁿ⁻ʳ
Find the chance the rth success occurs on trial n.
Worked example
- Required successes r
- 3
- Total trials n
- 5
- Success probability (%)
- 50
- Probability
- 18.75 %
- Expected trials
- 6
Scope and limitations
Use consistent units. The result follows the assumptions you enter.
Inputs are checked for missing values and allowed ranges. A result outside the finite numeric range is not displayed. Rounding affects display, while the calculation uses the model’s numeric precision.
Check your units and assumptions before relying on a result. Changing a label does not convert a currency or physical unit.
Formula version: 90b5b3a97288 · Example checked: