random values organization

hi there, 

the random component is producing random values between 0 and 50.

I am using this values as length of sdl lines along a curve (the curve is divided by 50)

I would like to control  the random results having the first ten curves with random length between 0-10, the second ten between 10-20, etc...

I am trying with graph mapper that is concentrate bigger values in some areas, but still getting big values randomly ( I have couple of maximum values in the first set of curves, witch I don't want).

any help? 

thank you!!!