Question

Suppose that the bank customers arrive randomly and independently on an average of 3.2

customers every 4 minutes. What is the probability that:

a. Exactly two customers arrive in every 4 minutes?

Answer 1

Let $X=$ the number of customers arrived: $X\sim Po(\lambda).$

Given $\lambda=3.2.$

$$P(X=2)=\dfrac{e^{-3.2}(3.2)^2}{2!}=0.208702$$