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Poisson distribution

The distance by motorway from A to B is 144 miles. For a motorist whose car is expected to break down once every 30,000 miles of motorway driving, and makes the round trip once a week, calculate the probability of having more than one break down in the same year.

I said that for every 288 miles, the number of expected breakdowns is 0.0096. How do I interpet the "in the same year" part of the question, I'm very confused?
Original post by KeyFingot
...


Since she makes the same trip every week for a year, annual mileage is...?
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KeyFingot
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Original post by ghostwalker
Since she makes the same trip every week for a year, annual mileage is...?


Ah I see, ~15000 miles right? thanks

I get 0.01 as the answer, do you mind checking this?
(edited 11 years ago)
Original post by KeyFingot
Ah I see, ~15000 miles right? thanks

I get 0.01 as the answer, do you mind checking this?


Agree with the mileage.

I got 0.09

Lambda was 0.4992.
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KeyFingot
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Original post by ghostwalker
Agree with the mileage.

I got 0.09

Lambda was 0.4992.


Oh I see, rounding errors! I used λ \lambda as 0.5 which is where the errors come in.

Thanks ghostwalker! :smile:
Original post by KeyFingot
Oh I see, rounding errors! I used λ \lambda as 0.5 which is where the errors come in.

Thanks ghostwalker! :smile:


Np, although, even with λ=0.5\lambda=0.5 I get 0.09. So I'd suspect finger problem on the calculator.

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