Question

the ratio of no of boys and girls in a school was 5:3.some new boys and girls were admitted to the school in the ratio 5:7.at this the total no of students in the school became 1200,and the ratio of boys to girls changed to 7:5.the no of students in the school before new admissions were how much?

Answer 1

Answer:

let boys = 5x  

girls = 3x  

students before admission = 8x  

let 5y boys and 7y girls be added to school  

total students = 8x + 12 y = 1200 ---------------- (1)  

new total boys/total girls = (5x + 5y) / (3x + 7y)

=>  7/5  

25x + 25 y = 21x + 49 y  

4x = 24y  

2x = 12 y  

put in (1)  

8x + 2x = 1200  

10 x = 1200  

x = 120  

8x = initial total students = 960

===================

@GauravSaxena01