# Question on Poisson

• November 15th 2009, 04:30 PM
I-Think
Question on Poisson
The number of serious faults on a randomly chosen 1km stretch of motorway has a Poisson distribution of mean 2.1. The random variable X km is the distance between successive serious faults on the motorway.

Explain, using a Poisson distribution, why for $x\geq0$
$P(X>x)=e^{-2.1x}$
• November 16th 2009, 03:16 AM
mr fantastic
Quote:

Originally Posted by I-Think
The number of serious faults on a randomly chosen 1km stretch of motorway has a Poisson distribution of mean 2.1. The random variable X km is the distance between successive serious faults on the motorway.

Explain, using a Poisson distribution, why for $x\geq0$
$P(X>x)=e^{-2.1x}$