Question

For which of the following probability of distribution are the mean and variance equal? (a) Normal (b) Gamma (c) Poisson (d) Binomial

Answer 1

Poisson distribution

We have both the mean, variance are defined to λ. & PMF of Poisson defined to

PMF of P.D is = f ( k ) $= e^{-λ} \frac{ λx }{ x!}$

Where  

λ = parameter of the distribution