Discrete Probability Distributions
Approximations

When n/N < 0.05 or N >=100, Hy (N, n, K) d b (n, p = k/N)

Example

A lot of N = 100 industrial products contains 40 defectives.  Let X be the number of defectives in a random sample of size 20.  Find p(10) by using:

1.      The hypergeometric probability distribution.

2.      The binomial probability distribution.

     Is N large enough so that the binomial probability function is a good approximation to the hypergeometric probability function?

Solution