Question 181886
In a warehouse, accidents have been taking place at the rate of 2 every 3 months. 
a) What probability distribution is most likely to model the number of accidents in a 3-month period? Give reasons for your choice that are related to the problem and give any parameters for the distribution. 
b) Find the mean and standard deviation of the number of accidents per year and what is the percentage of months with no accidents? 
c) If a month is chosen at random, find the probability of at least one accident. 

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Check to see what your text says about the Poisson distribution, or 
check it out on the internet.
I think it relates to your problem.
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Cheers,
Stan H.