Question

In a particular family, each boy has as many brothers as sisters but each girl has twice as many brothers as that of sisters. How many siblings are there in the family?

• A. $9$
• B. $7$
• C. $5$
• D. $4$

Answer 1

The correct option is B $7$

Let number of boys and girls in the family be $x$ and $y.$
Each boy has as many brothers as sisters.
$\Rightarrow x-1=y$
$\Rightarrow x-y=1\cdots \left(1\right)$
Also, each girl has twice as many brothers as that of sisters.
$\Rightarrow 2(y-1)=x$
$\Rightarrow 2y-x=2\cdots \left(2\right)$
From $\left(1\right)$ and $\left(2\right),$ we get
$x=4$ and $y=3$
$\therefore$ Number of boys and girls in the family are $4$ and $3$ respectively.