Question

One day in the playground,the ratio of the number of boy to the number of girl is 3:5 later 6girls come, 9boy leave, the ratio of the number of girl become 1:4. Find the difference between the number of boy and girl originally

Answer 1

The number of boys are 18 and the number of girls are 30.

Explanation:

The ratio of number of girls to the boys = 3 : 5

Let the number of girls is g and boys is b initially.

b : g = 3 : 5

5 b = 3 g ..... (1)

Now, girls are 6 + g and boys are b - 9

So, the ratio is

(b - 9) : (6 + g) = 1 : 4

4 b - 36 = 6 + g

4 b - g = 42 .... (2)

From ( 1 ) and ( 2 )

`4 b - \frac {5 b}{3}= 42\\\\(7 b )/(3) = 42\\\\b = 18`

And , g = 5 x 18/3 = 30

So, the number of boys are 18 and the number of girls are 30.