Question

Twenty cylindrical pillars of parliament house are to be cleaned . If the diameter of each pillar is 0.50m and height is 4m, what will be thecost of cleaning them at the rate of Rs2.50 per square metre?

Answer 1

Cleaning means wiping, right?
So,

In each pillar,
diameter, d= 0.5m
∴radius, r= d÷2 = 0.25m
height, h= 4m

For wiping the cylindrical pillars, we need to wipe the curved surface.
∴Curved surface area of 1 pillar= 2πrh
= 2 x 22/7 x 0.25 x 4 m²
= 2 x 22/7 x 25/100 x 4
= (22/7 x 2) m²

∴Curved surface area of 20 such pillars= 20 x (22/7 x 2) m²
≈125.71 m² (ANS)

Answer 2

Step-by-step explanation:

Hope this attachment helps u