Question

the number of boys and girls in a class are in the ratio of 7 ratio 5 the number of boys is 8 more than number of girls what is the total class strength

Answer 1

ratio is 7x:5x
total strength of class is 7x + 5x = 12x
no. of boys are; 7x = 5x + 8
7x + 5x = 8
2x = 8
x = 4
total no. of students = 12*4 = 48

Answer 2

Let
Boys = b
Girls = g 


The number of boys and girls in a class are in the ratio 7:5
b:g=7:5
b/g=7/5
b5=g7
b5/5=g7/5
b=g7/5...............(1) 
the number of boys is 8 more than the number of girls
b=g+8.............(2)
Put the value of b from (1) to (2)
g7/5=g+8
5*(g7/5)=5*(g+8)
g7=5g+40
g7-g5=40
2g=40
2g/2=40/2
g=20
Put the value of g in (2)
b=20+8
b=28 
Boys are 28 and Girls are 20




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