Probability Distributions.
2.71828), and k! is the factorial of k. Suppose a call center receives an average of 12 calls per hour. If you are interested in knowing the probability that exactly 15 calls are received in the next hour, you can use the Poisson distribution formula with λ=12 and k=15: P(X=15) = 1²¹⁵ * e^(-12) /