Linear Increment Across Fixed Distance

Hi all,

Could someone please give me a few pointers on how to solve the following:

I need to divide a 9mm distance into linearly incrementing portions, the first of which must measure 0.01mm and the last must measure 1.2mm.

As the size of each portion increments linearly across the entire 9mm distance, the rate increase must be constant from portion to portion, but how do I calculate this increment?

Any help would be most appreciated, as this problem is driving me insane :)

Thanks in advance, Carla.