Question

A cylindrical pillar is $50cm$ in diameter and $3.5m$ in height. Find the cost of painting the curved surface of the pillar at the rate of $12.50m^2$

Answer 1

Given: Height of cylindrical pillar $\left(h\right)$ is $3.5m$ and
Diameter $\left(d\right)$ is $50cm$

$\therefore$ Radius $\left(r\right)=\frac{d}{2}=25cmandh=2.5m$

C.S.A of the pipe is total radiating surface.

We know that,

C.S.A of right cylinder $=2\pi rh$

$=2\times \frac{22}{7}\times 2.5\times 3.5=\frac{11}{2}{m}^2$

$\because$ Cost of painting the $1m^2$ area $=Rs.12.50$

$\therefore \text{Total cost of painting the}\frac{11}{2}{m}^{2}area=Rs.\frac{11}{2}\times 12.50=Rs.68.75$

Hence, the cost of painting the curved surface is $Rs.68.75$.