Question

if the ratio of boys to girls in a class is x and the ratio of girls to boys is y then x+y​

Answer 1

Answer:

Let the number of boys be kx and the number of girls be ky.

Given,

k(x+y) = 4kx

=> x + y = 4x

=> y = 3x

The number of girls is kx, for any natural number k.

So in terms of x, the number of girls is kx, and in terms of y, the number of girls is ky/3.

Answer 2

Given : ratio of boys to girls = x

            ratio of girls to boys = y

To find : x + y

Solution :

Root number of boys be  'a' & girls be  'b'

than x = $\frac{a}{b}$ and

        y = $\frac{b}{a}$

than using Am − Gm inequality-

$\frac{\frac{x}{y} + \frac{y}{x} }{2}$  > $\sqrt{\frac{x}{y} * \frac{y}{x} }$ = 1

x + y ≥ 2

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