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Molbiotools is a collection of free online apps:

DNA Sequence Tools	Restriction Analyzer Silent Mutator Random Sequence Generator
Text and Data Tools	Target Text Extractor Multiple List Comparator List Operations Table Operations Two-table Operations Random Gene Set Generator
Lab Calculators	DNA Calculator Chemical Calculator Buffer Calculator Centrifugation
Math Calculators	Combinatorics Poisson Distribution Binomial Distribution Hypergeometric Distribution Geometric Distribution Negative Binomial Distribution

Poisson Distribution Calculator

A free online tool for calculating probabilities of events following Poisson distribution.

Independent random events occuring in a defined time interval or a defined length, area or space volume follow Poisson distribution with parameter λ equal to the average number of events per the defined time, length, space or volume unit. The probability P of seeing exactly x events during the defined time interval or in the defined length, space or volume unit is given by the formula:

P(X=x)

e^-λ

λ^x

λ≥0, x≥0

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Calculator

Expected (average) number of events:λ =

P(X = x):

P(X ≤ x):

P(X ≥ x):