Question

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

Answer 1

Diameter of cylindrical pillar = 50 cm

$\therefore$ Radius (r) = $\frac{50}{2}=25cm=\frac{1}{4}m$

and height (h) = 3.5 m

$\therefore$ Curved surface area = $2\pi$ rh

=$2\times \frac{22}{7}\times \frac{1}{4}\times 3.5m^2$

=$\frac{2\times 22\times 1\times 35}{7\times 4\times 10}{m}^2=\frac{11}{2}{m}^2$

Rate of painting the surface = Rs. 12.50 per $m^2$

$\therefore$ Total cost =Rs. $\frac{11}{2}\times$ 12.50 = Rs. 68.75