Question

The ratio of boys and girls in any class is 11:13. If 8 girls and 4 boys join the class , the ratio becomes 4:5. Find the number of students in the class- (ANSWER WITH SOLUTION)

a)108

b)120

c)96

d)240

Answer 1

Let the required ratio be x.

Given that number of boys in the class = 11x.

Given that number of girls in the class = 13x.

Given that 8 girls and 4 boys joined in the class.

Therefore the number of girls = 13x + 8

the number of boys = 11x + 4.

Given that the ratio becomes 4:5.

(13x + 8)/(11x + 4) = 5/4

(13x + 8) * 4 = 5(11x + 4)

52x + 32 = 55x + 20

-3x = -12

x = 4.

Number of girls = 13x + 8

                           = 13(4) + 8

                           = 60.


Number of boys = 11(4) + 4

                            = 44 + 4

                            = 48.


Therefore the number of students = 60 + 48

                                                           = 108


Hope this helps!

Answer 2

let no of boys be (eleven)x and no of girls be(thirteen)x
now (eleven)x+4/(thirteen)x+8=4/5
55x+20=52x+32
3x=twelve
x=4
boys (eleven)×4+4 i.e 48
girls (thirteen)×4+8 i.e 60
total student are
option a) one hundred eight
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