Question

There are $24$ students in Juan's class. The ratio of girls to boys is $1:2$. How many girls and boys are in Juan's class?

Answer 1

Determine the number of boys and girls in Juan's class.

Let us assume $g$ represents the number of girls and $b$ represents the number of boys in Juan's class.

It is given that the total number of student in Juhan's class is $24$.

$g+b=24\dots \left(1\right)$

The ratio of girls to boys is $1:2$.

$$\begin{gathered} g:b=1:2 \\ \Rightarrow \frac{g}{b}=\frac{1}{2} \\ \Rightarrow b=2g\dots \left(2\right) \end{gathered}$$

Substitute $2g$ for $b$ in equation $\left(1\right)$.

$$\begin{gathered} g+2g=24 \\ \Rightarrow 3g=24 \\ \therefore g=8 \end{gathered}$$

Substitute $8$ for $g$ in equation $\left(2\right)$.

$\begin{array}{rcl}b& =& 2·8\\ \therefore b& =& 16\end{array}$

Hence, the number of boys and girls in Juan's class are $\mathbf{16}$ and $\mathbf{8}$ respectively.