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Find the cost of sinking a tube well 280 m deep, having diameter 3 $m$ at the rate of Rs. 3.60 per cubic meter. Also find the cost of cementing its inner curved surface at Rs. 2.50 per square meter.

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Cost of sinking=Rs.4389, Cost of cementing=Rs.3455

Cost of sinking= Rs.5734, Cost of cementing=Rs.5234

Cost of sinking=Rs.5678, Cost of cementing=Rs.1456

Cost of sinking=Rs.7128, Cost of cementing=Rs. 6600

answer is D.

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Detailed Solution

It is given a tube well of depth 280 m, diameter 3 m and the cost of sinking the tube well is Rs.3.60 per cubic meter.
Also, the cost of cementing its inner curved surface is Rs.2.50 per square meter.
If r is the radius of the base and h is the height of the cylinder,
Then curved surface area =

2 π r h

If r is the radius of the base and h is the height of the cylinder, then
Volume =

π r 2 h

Radius =

D i a m e t e r 2

⇒

32 m

Volume =

π r 2 h

⇒ V o l u m e = 227 × 32 × 32 × 280 ⇒ V o l u m e = 1980 m 3

Since, rate of sinking the tube well = Rs. 3.60 per

m 3

So, the total cost of sinking

= R s . 1980 × 3.60

⇒

Total cost of sinking

= R s . 7, 128

Curved surface area =

2 π r h

⇒

Curved surface area

= 2 × 227 × 32 × 280

⇒

Curved surface area

= 2640 m 2

Since, rate of cementing = Rs. 2.50 per

m 2

So, the total cost of cementing

= R s . 2.50 × 2640

⇒

Total cost of cementing

= R s . 6, 600

Therefore, the cost of sinking the tube well is Rs.7128 and the cost of cementing the inner surface area of the tube well is Rs.6600.
Hence option (4) is correct.

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