There are 20 cylindrical pillars in a building, each having a diameter

1.	There are 20 cylindrical pillars in a building, each having a diameter of 50cm and height 4m. Find the cost of cleaning them at ₹ 14 per m2.
Answer» It is given that Diameter of one pillar = 50cm = 0.5m So the radius of one pillar = 0.5/2 = 0.25m Height of one pillar = 4m We know that Lateral surface area of one pillar = 2 πrh By substituting the values Lateral surface area of one pillar = 2 × (22/7) × 0.25 × 4 So we get Lateral surface area of one pillar = 6.285 m² So the lateral surface area of 20 pillars = 20 × 6.285 = 125.714 m² It is given that the cost of cleaning = ₹ 14 per m² So the cost of cleaning 125.714 m² = ₹ (14 × 125.714) We get Cost of cleaning 125.714 m² = ₹ 1760 Therefore, the cost of cleaning 125.714 m² is ₹ 1760.

There are 20 cylindrical pillars in a building, each having a diameter of 50cm and height 4m. Find the cost of cleaning them at ₹ 14 per m2.

Answer»

It is given that

Diameter of one pillar = 50cm = 0.5m

So the radius of one pillar = 0.5/2 = 0.25m

Height of one pillar = 4m

We know that

Lateral surface area of one pillar = 2 πrh

By substituting the values

Lateral surface area of one pillar = 2 × (22/7) × 0.25 × 4

So we get

Lateral surface area of one pillar = 6.285 m²

So the lateral surface area of 20 pillars = 20 × 6.285 = 125.714 m²

It is given that the cost of cleaning = ₹ 14 per m²

So the cost of cleaning 125.714 m² = ₹ (14 × 125.714)

We get

Cost of cleaning 125.714 m² = ₹ 1760

Therefore, the cost of cleaning 125.714 m² is ₹ 1760.