how average time is calculated in load lest?I am getting some strange result...

Hi,

I want to calculate an average time for a load test using SOAP UI pro.
I am using Simple strategy with 10 threads and limit as total run =20.
I am getting results something like -
Min - 20
Max- 4000
and avg - approx 200 to 350.

I dont know how this average time figure is calculated .
Can anyone explain me  how it is calculated and on what parameters it is dependent?

A simple example will be helpful.

Thanks,
Archana