======================================================
Work Shown:
(160 with blue eyes)/(500 total) = (x with blue eyes)/(2500 total)
160/500 = x/2500
x = 2500*(160/500)
x = 800
------------
Another approach:
160/500 = 0.32 = 32% of the first group has blue eyes
Assuming this percentage is the same for any group, then,
32% of 2500 = 0.32*2500 = 800 people of the second group are estimated to have blue eyes, of the 2500 total.