Question

The ratio of girls and boys in a class is $1:3$, set up an equation between the students of a class and boys and then draw its graph also find the number of boys in a class of $40$ student from the graph.

Answer 1

Let no. of girls $=x$

$\Rightarrow$ no. of boys $=3x$.

$\Rightarrow$ no. of students in class $=4x$

$=\frac{4}{3}\times 3x$

$=\frac{4}{3}\times no.ofboys$

Let $y$ represent no. of students and $x$ represent no of boys.

$\Rightarrow y=\frac{4}{3}x$

$\Rightarrow y=mx$ form

It is a straight line with slope $4/3$ and passing through origin.

$x,y$ cannot be negative

So, graph in $1^{st}$ Quadrant Must be considered.

Given, $y=40$

$\Rightarrow \frac{4x}{3}=40$

$\Rightarrow x=30$

$\Rightarrow$ No. of boys $=30$.