Question

In a building there are $24$ cylindrical pillars. The radius of each pillar is $28cm$ and height is $4m$. Find the total cost of painting the curved surface area of all pillars at the rate of $8$ per $m^2$

Answer 1

Radius of cylindrical pillar, $r=28cm=0.28m$

Height of cylindrical pillar, $h=4m$

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

Curved surface area of a pillar $=2\times \frac{22}{7}\times 0.28\times 4=7.04m^2$

Curved surface area of 24 such pillar $=7.04\times 24=168.96m^2$

Cost of painting an area of $1m^2=Rs.8$

Therefore, cost of painting $1689.6m^2$

$=168.96\times 8=Rs.1351.68$