# Math Help - [SOLVED] Variance of the poisson distribution

1. ## [SOLVED] Variance of the poisson distribution

Suppose Y~Poi(t) <-- can't really type the character lambda.
What is the Variance of Y?

I know that variance is equal to E(Y^2) - (E(Y))^2
E(Y) = t, for poissan distributions
However, how do I find E(Y^2)? It's not just t^2, is it?

2. Originally Posted by mistykz
Suppose Y~Poi(t) <-- can't really type the character lambda.
What is the Variance of Y?

I know that variance is equal to E(Y^2) - (E(Y))^2
E(Y) = t, for poissan distributions
However, how do I find E(Y^2)? It's not just t^2, is it?