Question

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

Answer 1

Diameter$=D=50\text{cm}$

Radius of cylinder $=r=\frac{D}{2}=\frac{50}{2}\text{cm}=25\text{cm}=0.25\text{m}$

Height of cylinder, $h=3.5\text{m}$

Curved Surface Area of cylinder $=2\pi rh$

$=2\pi (0.25\times 3.5){\text{m}}^2=5.5{\text{m}}^2$

Cost of painting per meter square $=\text{Rs.}12.50$

Total cost of painting $5.5{\text{m}}^2=\text{Rs.}12.50\times 5.5=\text{Rs.}68.75$