Question

A storage tank consists of a circular cylinder with a hemisphere adjoined on one end. If the external diameter of the cylinder is $1.4m$ and its length be $5m$, find the cost of painting it on the outside including the base at the rate of Rs. $10$ per $m^2$.

Answer 1

External diameter of the cylinder $=1.4m$

Radius $r=\frac{1.4}{2}=0.7m$

Height of the cylinder $h=5m$

Curved surface area of the cylinder $=2\pi rh$

$=2\times \frac{22}{7}\times 0.7\times 5m^2$

$=22m^2$

Area of the base of the tank $=\pi r^2$

$=\frac{22}{7}\times {0.7}^2{m}^2$

$=1.54m^2$

Curved surface area of the hemisphere $=2\pi r^2$

$=2\times \frac{22}{7}\times {0.7}^2{m}^2$

$=3.08m^2$

Total outer area to be painted $=(22+1.54+3.08)m^2$

$=26.62m^2$

Cost of painting $=Rs.10\times 26.62$

$=Rs.266.2$