Question

A random variable X has a Poison distribution with mean equal to 0.4. What is the probability the probability that the random variable is greater than zero.

Answer 1

For a poisson distribution,

$P(X=x) =\frac {e^\lambda \lambda ^x} {x!}$

$\lambda=0.4$

P(X>0)=1-P(X=0)

$=1-\frac {e^{-0.4} 0.4^0}{0!}$

=$1-e^{-0.4}$

=1-0.6703

=0.3297