Answer:
18.88% probability that three or four customers will arrive during the next 30 minutes
Step-by-step explanation:
In a Poisson distribution, the probability that X represents the number of successes of a random variable is given by the following formula:
![P(X = x) = \frac{e^{-\mu}*\mu^{x}}{(x)!}](https://tex.z-dn.net/?f=P%28X%20%3D%20x%29%20%3D%20%5Cfrac%7Be%5E%7B-%5Cmu%7D%2A%5Cmu%5E%7Bx%7D%7D%7B%28x%29%21%7D)
In which
x is the number of sucesses
e = 2.71828 is the Euler number
is the mean in the given time interval.
Average rate of 6.4 per 30 minutes.
This means that ![\mu = 6.4](https://tex.z-dn.net/?f=%5Cmu%20%3D%206.4)
What is the probability that three or four customers will arrive during the next 30 minutes?
![P = P(X = 3) + P(X = 4)](https://tex.z-dn.net/?f=P%20%3D%20P%28X%20%3D%203%29%20%2B%20P%28X%20%3D%204%29)
![P(X = x) = \frac{e^{-\mu}*\mu^{x}}{(x)!}](https://tex.z-dn.net/?f=P%28X%20%3D%20x%29%20%3D%20%5Cfrac%7Be%5E%7B-%5Cmu%7D%2A%5Cmu%5E%7Bx%7D%7D%7B%28x%29%21%7D)
![P(X = 3) = \frac{e^{-6.4}*(6.4)^{3}}{(3)!} = 0.0726](https://tex.z-dn.net/?f=P%28X%20%3D%203%29%20%3D%20%5Cfrac%7Be%5E%7B-6.4%7D%2A%286.4%29%5E%7B3%7D%7D%7B%283%29%21%7D%20%3D%200.0726)
![P(X = 4) = \frac{e^{-6.4}*(6.4)^{4}}{(4)!} = 0.1162](https://tex.z-dn.net/?f=P%28X%20%3D%204%29%20%3D%20%5Cfrac%7Be%5E%7B-6.4%7D%2A%286.4%29%5E%7B4%7D%7D%7B%284%29%21%7D%20%3D%200.1162)
![P = P(X = 3) + P(X = 4) = 0.0726 + 0.1162 = 0.1888](https://tex.z-dn.net/?f=P%20%3D%20P%28X%20%3D%203%29%20%2B%20P%28X%20%3D%204%29%20%3D%200.0726%20%2B%200.1162%20%3D%200.1888)
18.88% probability that three or four customers will arrive during the next 30 minutes