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Rup
December 25th 2005, 01:40 PM
For this example I am getting 2e^(-2) and answer says 3e^(-2).

The number of power surges in an electric grid has a Possion distribution with mean of 1 power surge every 12 hours. What is the probability that there will be no more than 1 power surge in 24 –hour period?

Can anybody verify?

Thanks

Rup

Sam Broverman
December 25th 2005, 01:51 PM
The number of power surges in 24 hours will have a Poisson
distribution with a mean of 2. Saying that there are no more than 1 power surge in 24 hours is the same as saying that there are either 0
or 1 power surges in 24 hours. The probability of 0 power surges in
24 hours is e^(-2) , and the probability of 1 power surge in 24
hours is 2e^(-2) .

Remember that for the Poisson random variable N
with mean c, the probability P(N=k) is (c^k)(e^(-c))/k! .

In this case P(N=1) = (2^1)(e^(-2))/1! = 2e^(-2) .
Then P(N=0 or 1) = 3e^(-2) .

Rup
December 25th 2005, 03:36 PM
Thanks, Sam! It was helpful.