Probability Distributions Visualizer

Explore binomial, Poisson, geometric, and uniform distributions. Adjust parameters and see the probability mass function, mean, and variance update instantly.

Distribution Parameters

10
0.50

Properties

Distribution--
PMF--
Parameters--
Mean--
Variance--
Std Dev--

The Math Behind It

Discrete Distributions

  • Binomial: P(X=k) = C(n,k) pk(1-p)n-k — n trials, probability p of success
  • Geometric: P(X=k) = (1-p)k-1 p — trials until first success
  • Uniform: P(X=k) = 1/n — equal probability for all outcomes
  • Each distribution has a probability mass function (PMF) that sums to 1
  • Mean and variance characterize the center and spread

Poisson Distribution

  • Models the count of rare events in a fixed interval
  • P(X=k) = λk e / k!
  • λ is the expected rate (average count)
  • Key property: mean = variance = λ
  • For large λ, the Poisson approaches a normal distribution
  • Used for traffic arrivals, radioactive decay, server requests