Hi!
I am aware of the steps used to show that (e^-λ*λ^r)/r! is P(X=r) for X~Po(λ), where λ = E(X) = Var(X). I have two questions regarding this:
- I'm aware that all of the probabilities add up to 1, but how do we know that they're all probabilities and not just a set of values that add to 1...