Question

The ratio of boys to girls in a club is $7:4$. There are $21$ fewer girls than boys. What is the total number of children in the club?

• A. $49$
• B. $77$
• C. $84$
• D. $231$

Answer 1

Answer: (B)

$77$

Let number of boys be $x$ and number of girls be $y$.

Then, it is given that,

$\frac{x}{y}=\frac{7}{4}$

$\Rightarrow 4x=7y$ .......... (1)

$x-y=21$

$\Rightarrow x=21+y$ .......(2)

Substituting (2) in (1), we get,

$4(21+y)=7y$

$\Rightarrow 7y-4y=84$

$\Rightarrow y=\frac{84}{3}=28$

Hence, $x=21+y=49$

Therefore, $x+y=49+28=77$