POISSON DISTRIBUTION

Poisson Approximation to the Binomial Distribution

m = np for large values of n and small values of p (p?.1)

Example:

1% of people colour-blind. What is the probability that 10 or more randomly chosen will be colour-blind?

Solution:

We cannot use Binomial table since (n=500) is too large.

Using Poisson approximation:

m = np =

p(9 or fewer colour-blind in 500) =

p(10 or more colour-blind in 500)