Poisson Distribution

Poisson Distribution is used when there is a certain number of something per something. There are some formula that we can use to find the probability. As well as this we can also use the calculator. When using this distribution we make some assumptions of the data. These are that the:

• Occurrence of the event is independent
• Number of items or events is proportional to the area or time etc.
• Items or events cannot occur at the same time or the same space

The symbols used in this distribution are:

λ = Mean

x = Particular number we want to find

e = Mathematical constant = 2.71828...

The formula of this distribution are:

P(X=x) =( λe⌃(-λ))/(x!)

μ = λ

σ = √λ

To find the probability on the calculator we use the Poisson setting. To get to this screen go into menu, stats, dist, poisn, Ppd. Then enter the values you know. Ppd is used when you are trying to find the probability that it is exactly something. Use Pcd when you are trying to find the probability it is up to.