Assume that the number of new visitors to a website in one hour is distributed as a Poisson variable with λ = 4.0. What is the probability in any given hour that there are no new visitors to the website?

Step-by-step explanation:

Previous concepts

Let X the random variable that represent the number of new visitors to a website in one hour. We know that

The probability mass function for the random variable is given by:

And f(x)=0 for other case.

For this distribution the expected value is the same parameter

Solution to the problem

On this case we are interested on the probability of having no visitors to the website:.

Using the pmf we can find this probability like this: