Answer: c. 0.1743
Step-by-step explanation: Poisson Probability or Poisson Distribution is a discrete distribution that models the number of events ocurring in a given period of time.
The mean, or expected value, of the observed frequencies is:
E(X) = ∑xP(x)
E(X) = 0*3/150 + 1*(10/150) + 2*(15/150) + 3*(23/150) + 4*(30/150) + 5*(24/150) + 6*(20/150) + 7*(13/150) + 8*(8/150) + 9*(4/150)
E(X) = 4.399
The Poisson distribution is calculated by:
P(X = k) = [tex]\frac{mean^{k}.e^{-mean}}{k!}[/tex]
The question asks for the expected frequency of exactly 3 cars:
P(X = 3) = [tex]\frac{4.399^{3}.e^{-4.399}}{3!}[/tex]
P(X = 3) = [tex]\frac{4.399^{3}.e^{-4.399}}{3.2.1}[/tex]
P(X = 3) = 0.1743
The expected frequency of exactly 3 cars is 0.1743
