Use the Poisson Distribution to find the indicated probability.
-A mountain search and rescue team receives a mean of 0.78 calls per day. Find the probability that on a randomly selected day, they will receive fewer than two calls.
A) 0.1840
B) 0.1394
C) 0.8160
D) 0.3576

Question

Quizplus · Accepted Answer

We use the Poisson distribution with parameter λ = 0.78. Then, 
P(X < 2) = P(X = 0) + P(X = 1) = e^(-λ)λ^0/0! + e^(-λ)λ^1/1! = e^(-0.78) + 0.78e^(-0.78) ≈ 0.8160. Therefore, the best choice is C.

Use the Poisson Distribution to Find the Indicated Probability