Question

there are 720 students in a school the ratio of the number of boys to girl is 7:2 . if 40 new boys are admitted, find how many new girls should be admitted so that the ratio of the number of boys to the number of girls may be changed to 10:3

Answer 1

No of students = 720

Ratio between girls and boys = 7 : 2

Let the common multiple be x.

So, no of girls = 2x and no of boys = 7x

-> 7x + 2x = 720

=> 9x = 720

=> x = 720 / 9

=> x = 80

Therefore, no of girls = 2 x 80 = 160 and no of boys = 7 x 80 = 560

Given,New boys added = 40

So, no boys = 560 + 40 = 600

Let y girls be added.

So, no of girls = (160 + y)

A.C.Q., (160 + y) / 600 = 10 / 3

=> 3 ( 160 + y ) = 10*600

=> 480 + 3y = 6000

=> y = (6000-480)/3

=> y=1840

so, 1840 girls are to be admitted to make the ratio of boy: girl=10:3

Answer 2

Answer:

y= 20

Step-by-step explanation: