Question

the ratio of the no. of boys to the no. of girls in school of 720 student is 3 : 5. if 18 new girls are admitted in the school, find how many new boys many admitted so that the ratio of the no. of the no. of girls many change to 2 : 3

Answer 1

Ratio of no. girls to no. of boys = 3:5

➢ Let no. of girls = 3x

➢ Let no. of boys = 5x

➢ Let this ratio be = 3x:5x

Total no. of students = 270

↣ 3x + 5x = 270

↣ 8x = 270

↣ x = 270/9

↣ x = 90

∴ No. of girls = 3×90 = 270

∴ No. of boys = 5×90 = 450

➢ Now, 18 boys are added.

No. of boys = 468

Let the new ratio of no. girls to no. of boys=2x:3x

↣ 3x = 468

↣ x = 468/3

↣ x = 156

∴ New no. of girls = 156 × 2 = 312

∴ No. of girls to be added = 312-270 = 42

Your answer = 42