Question

20 cylindrial PILLARS ARE TO BE CLEANED IF THE DIAMETER OF EACH IS 0.5m and the height is 4m what will be cost of cleaning at the rate of rs 2.5 per m²

Answer 1

Answer:

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

Answer:

Hey , here is your answer step-by-step :

Step-by-step explanation:

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