If X∼Poisson(λ)X \sim \text{Poisson}(\lambda)X∼Poisson(λ), what is the coefficient of variation (CV=σμCV = \frac{\sigma}{\mu}CV=μσ)?
1λ\frac{1}{\lambda}λ1
1λ\frac{1}{\sqrt{\lambda}}λ1
λ\sqrt{\lambda}λ
111