Solution(By Examveda Team)

$$\eqalign{ & \text{Number of students in:} \cr & \text{A → } \frac{12}{100}\times6000 = 720 \cr & \text{B → } \frac{9}{100}\times6000 = 540 \cr & \text{C → } \frac{26}{100}\times6000 = 1560 \cr & \text{D → } \frac{18}{100}\times6000 = 1080 \cr & \text{E → } \frac{29}{100}\times6000 = 1740 \cr & \text{F → } \frac{6}{100}\times6000 = 360 \cr} $$

Number of boys in:
A → 500
B → 400
C → 900
D → 600
E → 1200
F → 100

Number of girls in:
A → 720 - 500 = 220
B → 540 - 400 = 140
C → 1560 - 900 = 660
D → 1080 - 600 = 480
E → 1740 - 1200 = 540
F → 360 - 100 = 260

Required ratio
= 900 : 140 : 1740
= 90 : 14 : 174
= 45 : 7 : 87