Exponential Distribution

[SarahLi]

Hey Everyone,

 

What does it mean if the processing time of a certain job instance is generated according to an exponential distribution with a certain mean? I already know the mean so what does it add to know its distribution and how can I use it?

 

Regards,

[studiot]

Well this is a continuous distribution of the probability density function p(x) for x>0 (it is zero for x<0)

 

[math]p(x) = \lambda {e^{ - \lambda x}}[/math] :x > 0:lambda > 0

It has one parameter, lambda which is positive.

 

The mean is given by

[math]Mean = \frac{1}{\lambda }[/math]

and the variance by

[math]Variance = \frac{1}{{{\lambda ^2}}}[/math]

 

As you can see, the probability falls with increasing x so you might use this distribution to model say your chances of living x years beyond 100 years of age.

Edited September 6, 2014 by studiot