Question 971798: Every week the average number of wrong-number phone calls received by a certain mail-order house is seven. What is the probability that they will rêcive 2 wrong phone calls tomorrow?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! On first look, there isn't enough information, but this could fit a Poisson distribution. There are discrete numbers, they are random, and theoretically, there could be an infinite number.
The probability for 2 calls in one day, when they average 1 a day is about 0.18
It comes from the sum from 0 to infinity lambda ^x exp(-lambda)/x! Where in this instance lambda is 1. The probability of 2 is exp^(-1) 1^2/2!, and that is (1/2) (1/e) or about 0.18.
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