Question

In a building there are 36 cylindrical pillars.The radius of each pillar is 56 cm and height is 400 cm.Find the total cost of painting the curved surface area of the pillars at the rate of rs 8 per m

Answer 1

The curved surface area of a cylinder is equal to:

A=2πr× Height

r=56cm

H=400cm

A=2 ×56×22/7 × 400=352cm × 400cm

Convert into meters before performing multiplication.

1m=100cm

352/100=3.52 400/100=4m

A=3.52 × 4=14.08m² for one pillar.

For 36 Pillars we have :

14.08 × 36=506.88m²

1m² =Rs8

506.88m² =?

By cross multiplication we have :

506.88×8=4055.04

Rs 4055.04

Answer 2

Mistake in the question : In question it is Given rate = ₹ 8 per m. But RATE should be = ₹ 8 per m² Given:
Radius of cylindrical pillar = 56 cm
Height of cylindrical pillar = 400 cm
Rate of painting the cylindrical pillar = ₹ 8 per m.

Curved Surface area of cylinder = 2πrh
= 2 × (22/7) × 56 × 400
= 44 × 8 × 400 = 44 × 3200= 140,800 cm²
CSA of Cylinder = 140800 cm²
CSA of Cylinder = 140800 /10000 = 14.08 m²
[ 1cm² = 1/10000 m²]
CSA of 36 Cylinder = 36 × 14.08 = 506.88 m²

Cost of painting the curved surface area of the pillars = CSA of 36 Cylinder × Rate
Cost of painting the curved surface area of the pillars = 506.88 × 8 = ₹ 4,055.04

Hence, the Cost of painting the curved surface area of the pillars is ₹ 4,055.04.

HOPE THIS WILL HELP YOU..