Question

In a building there are 32 cylindrical pillars.. If each pillar has a circular base of radius 25 cm and height 10.5 m, then find the total cost of painting the curved surface area of all the pillars at the rate of ₹8 per meter square​

Answer 1

Given:-

• In a building there are 32 cylindrical pillars.
• Base radius = 25 cm
• Height = 10.5 m

To Find:-

• The total cost of painting the curved surface area of all the pillars at the rate of ₹8 per meter square.

Solution:-

Let us first calculate the CSA of one pillar.

Given dimensions:-

• Base radius = 25 cm
• Height = 10.5 m

Let us convert the unit of base radius into m.

We know,

1 cm = 1/100 m

Hence,

25 cm = 25/100 = 0.25 m

Now,

We know,

• CSA of cylinder = 2πrh sq.units

Hence,

CSA of one pillar = 2 × 22/7 × 0.25 × 10.5

CSA = 2 × 22 × 0.25 × 1.5

CSA = 16.5 m²

∴ CSA of 1 pillar = 16.5 m²

Now,

If CSA of 1 pillar = 16.5 m²

Then,

CSA of 32 pillars = 16.5 × 32

CSA of 32 pillars = 528 m²

∴ CSA of 32 pillars is 528 m².

It is already given that:-

Cost of painting 1 m² = Rs.8

Hence,

Cost of painting 528 m² = 8 × 528

Cost of 528 m² = 4224.

∴ Cost of painting 32 pillars is Rs.4224.

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