# Poisson Distribution question

1. Apr 29, 2007

### tiger2380

Can someone help me with this question:
If X has a Poisson distribution so that 3P(X=1)=P(X=2)
find the pdf of X, and P(X=4)????

2. Apr 29, 2007

### robert Ihnot

"pdf," I assume means Poisson Distribution Function.

Well, the function is $$P(n)=\frac{e^{-\kappa}\kappa^n}{n!}$$

So since we know values of n, the important thing is to find the particular value of the constant $$kappa, \kappa$$

Last edited: Apr 29, 2007
3. Apr 30, 2007

### mathman

It looks like k=6.