Thank you very much. That was very clear. 
In the mean time I searched around on google.<p>The property of this proof of work is that the duration of the work is random.<p>How is it possible to know the average work time duration, without doing the measurement ?
Is it possible to provide a work time limit so that if a client has really bad luck and can&#x27;t find the solution in that period can he can issue another question ?<p>From the ur perspective, this varying work time duration may be an unpleasant experience.