Question

In a building there are 24 cylindrical pillars. The radius of each pillar is 28 cm and height is 4m. Find the total cost of painting the curved surface area of all pillars at the rate of Rs.8 per m².​

Answer 1

ANSWER

C.S.A. of cylindrical =2πrh

⇒ C.S.A. of are pillar =2×

7

22

×28×4=704cm

2

⇒ C.S.A. of 24 pillars =24×704=16896cm

2

=16896×10

−4

m

2

=1.69m

2

⇒ Total cost Rs. 8×1.69=Rs.13.52

PLEASE MARK AS BRAINLIST

Answer 2

Given:-

⌬ Radius = 28 cm = 0.28m

⌬ Height = 4m

⠀

To find:-

⌬ Total cost of painting the curved surface area of all pillars at the rate of Rs.8 per m².

⠀

Solution:-

★ Using Formula

${\boxed{\sf{\orange{C.S.A\: of\: a\: cylinder = 2\pi rh}}}}$

⠀

C.S.A of a pillar = $2 × \sf{\dfrac{22}{7} × 0.28 × 4}$

⠀⠀⠀⠀⠀⠀⠀⠀⠀ $\sf{= 7.04m^2}$

C.S.A of 24 such pillar = $\sf{7.04 × 24}$

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀ $\sf{= 168.96m^2}$

Cost of painting an area of 1m² = $\sf{Rs.8}$

Therefore,

Cost of painting $\sf{1689.6m^2}$ = $\sf{1689.6 × 8}$

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀$\sf{= Rs.1351.68}$

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