The probability that, for any day, the number of special orders sent out will be exactly 3 is 0.1633.
<h3>What are some of the properties of Poisson distribution?</h3>
The Poisson distribution is a discrete probability distribution that describes the likelihood of a specific number of events occurring in a specified span of time or space, if these events occur at a constant mean rate and regardless of the time since the last occurrence.
Let X ~ Pois(λ)
Then we have:
E(X) = λ = Var(X)
Since standard deviation is the square root (positive) of variance,
Thus,
The standard deviation of X = ![\sqrt{\lambda}](https://tex.z-dn.net/?f=%5Csqrt%7B%5Clambda%7D)
Its probability function is given by
![f(k; λ) = Pr(X = k) = \dfrac{\lambda^{k}e^{-\lambda}}{k!}](https://tex.z-dn.net/?f=f%28k%3B%20%CE%BB%29%20%3D%20Pr%28X%20%3D%20k%29%20%3D%20%20%20%5Cdfrac%7B%5Clambda%5E%7Bk%7De%5E%7B-%5Clambda%7D%7D%7Bk%21%7D)
Given the mean is 4.2.
We have to find the probability that on any day, the number of special orders sent out will be exactly 3. Therefore, the value of x will be 5.
Using the Poisson distribution,
![P(x) = \dfrac{e^{-\lambda}\lambda ^x}{x!}\\\\P(5) =\dfrac{e^{-4.2}(4.2)^5}{5!}\\\\P(5) = 0.1633](https://tex.z-dn.net/?f=P%28x%29%20%3D%20%5Cdfrac%7Be%5E%7B-%5Clambda%7D%5Clambda%20%5Ex%7D%7Bx%21%7D%5C%5C%5C%5CP%285%29%20%3D%5Cdfrac%7Be%5E%7B-4.2%7D%284.2%29%5E5%7D%7B5%21%7D%5C%5C%5C%5CP%285%29%20%3D%200.1633)
Hence, the probability that, for any day, the number of special orders sent out will be exactly 3 is 0.1633.
Learn more about Poisson distribution here:
brainly.com/question/7879375
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