Hypergeometric Distribution

Overview

  • The Hypergeometric distribution models the probability of drawing a specific number of successes (items of interest) from a finite population without replacement.
  • It is commonly used in situations where you have a finite population and want to calculate the probability of drawing a certain number of items of interest in a sample without replacement.

Use Case

  • Used in various fields such as quality control (sampling from a production batch), biology (sampling from a population of organisms), and genetics (calculating probabilities of inheritance).

Formula

  • Probability Mass Function (PMF):
    • ( K ): Total number of items of interest in the population
    • ( N ): Total population size
    • ( n ): Sample size
    • ( k ): Number of items of interest in the sample

Example

  • Quality Control:
    • Suppose a production batch contains 20 defective items out of 100.
    • We randomly sample 5 items from the batch without replacement.
    • We want to find the probability of obtaining exactly 2 defective items in the sample.
    • Using the Hypergeometric PMF: