Question

8. A circular tunnel of diameter 2 m and length 1.4 km is dug out. Find the cost of plastering
it at 150 per 100 m²
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Answer 1

Answer:

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Diameter of the circular tunnel = 2 m =

Then, radius of the circular tunnel = 2/2 = 1m

Length or height of the circular tunnel = 1.4 km or 1400 m

As the circular tunnel is in the shape of a right circular cylinder.

Curved surface area of cylinder = 2rh

- 2*22/7*1*1400

= 8800 m2

Cost of plastering the tunnel = Rs. 150 per 100 m?

Total cost of plastering = (8800*150)/100

= Rs. 13200

So, the total cost of plastering will be Rs. 13200