Answer :
The expected number of failures in 1 year is 8.9948.
The authors calculate a failure rate for PVC pipe of 0.0081 per 100 miles of pipe per day in 2008. Think of a 100-mile section of this pipe.
(I)
Given;
Mean failures per day = 0.0081
So,
Expected number of failures in 1 year = 0.0081 * 365
= 8.9948
(II)
Poisson Distribution with λ = 8.9948 is given by:
[tex]P(x) =\frac{e^-^8^.^9^9^4^8 8.9948^0}{x!}[/tex]
⇒ for x = 0, 1, 2,. . . .
P(At least 1 failure) = 1- P(X=0);
[tex]P(x) = \frac{e^-^8^.^9^9^4^8 8.9948^0}{0!} = \frac{0.00012*1}{1}[/tex]
= 0.00012
So,
P(At least 1 failure) = 1 - 0.00012 = 0.99988
Hence, the expected number of failures in 1 year is 8.9948.
To learn more about Poisson Distribution click here:
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