Question

5. There are 20 cylindrical pillars in a building, each having a diameter of
50 cm and height 4 m. Find the cost of cleaning them at 14 per m^2​

Answer 1

Answer:

Rs 1760

Step-by-step explanation:

Radius of 1 pillar = 50/2 cm    

             = 25 cm  = 0.25 m

                 

Curved surface of 1 pillar is 2πrh

       = 2 x (22/7) x (0.25) x 4 m²

       = 44/7  m²

∴ Curved surface area of 20 such pillars 20 x 44/7 m² = 880/7  m²

Cost of cleaning = rate x area

            = Rs 14 x (880/7)

            = Rs 1760

Answer 2

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Given :-

• Radius of 1 pillar = 50/2 cm    

             ⟹ 25 cm  = 0.25 m

                 

• Curved surface of 1 pillar is 2πrh

       ⟹ 2 x (22/7) x (0.25) x 4 m²

       ⟹ 44/7  m²

Therefore, Curved surface area of 20 such pillars 20 x 44/7 m² = 880/7  m².

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Answer :-

• Cost of cleaning = rate x area

            ⟹ Rs 14 x (880/7)

            ⟹ Rs 1760

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