The Environment Protection Agency (EPA) limits the amount of vinyl chloride in the plant air emissions
to no more than 10 parts per millions. Suppose a mean emission of vinyl chloride for a particular plant is 4
parts per million. Assume the number of parts per million of vinyl chloride in air sample x, follows a
Poisson probability distribution:
a) What is the standard deviation of the plant?
b) Is it likely that a sample of air from the plant would yield a value of x that would exceed the
EPA limit? Explain. Note that P(x≤9) = 0.991868