A line graph of cost ($\rupee$) vs. number of pencils $n$ is a straight line through the origin. If $4$…
A line graph of cost ($\rupee$) vs. number of pencils $n$ is a straight line through the origin. If $4$ pencils cost $\rupee\,12$, the cost of $9$ pencils is:
$\rupee\,21$
$\rupee\,24$
$\rupee\,27$
$\rupee\,30$
Solution
Unit cost $=12/4 = \rupee\,3$ per pencil. So $9$ pencils cost $9 \times 3 = \rupee\,27$.