Question

(i) How many cubic metres of soil must be dug out to make a well 20 metres deep
and 2 metres in diameter?
(ii) If the inner curved surface of the well in part (i) above is to be plastered at the
rate of ₹50 per ma, find the cost of plastering.​

Answer 1

Answer:

Given that,

height(h)=20m

diameter (d)=2m

radius (r)=2/2=1m

Volume of the cylinder=πr²h

=3.14×1×1×20

=31.4×2

=62.8m³

The cost of plastering per my=50Rs

the cost of plastering for 62.8m³=62.8×50

=628×5=3140Rs

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Answer 2

volume of soil = volume of well

                    = pi*r²*h

                    = (22/7)1²*20

                     = 62.857 m³.

curved surface area of well = 2*pi*r*h

                                      = 2(22/7)*1*20

                                     = 125.714 m².

cost of plastering = 50*125.714 =  Rs. 6285.7

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