Answer:
Let the initial number of boys and girls be 600 and 800 respectively, so that
(no. of boys) : (no. of girls) = 6:8.
Final number of boys (Fb) = 600+ 20% of 600 = 720
Final number of girls(Fg) = 800+ 10% of 800 = 880
The new ratio = Fb / Fg = 720 / 880 = 9/11 = 9:11
So, the new ratio will be 9 : 11