Urgent STAT probability?

On the average, 6.7 cars arrive at the drive-up window of a bank every hour. Define the random


variable X to be the number of cars arriving in any hour.





a. What is the appropriate probability distribution for X? Explain how X satisfies the properties of


the distribution.


b. Compute the probability that exactly 5 cars will arrive in the next hour.


c. Compute the probability that no more than 5 cars will arrive in the next hour.

Urgent STAT probability?
a. This a Poisson distribution. I'll let you explain why. I have to assume you know what a Poisson distribution is and how to apply the formulas.





b. Pr(X=5) = [e^(-6.7)*6.7^5]/5! = 0.13849...





c. Pr(X%26lt;=5) = Pr(X=5) + Pr(X=4) + Pr(X=3) + Pr(X=2) + Pr(X=1) + Pr(X=0)


= e^(-6.7)*[6.7^5/5! + 6.7^4/4! + 6.7^3/3! + 6.7^2/2! + 6.7 + 1]


= 0.340649...

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