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# (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 Rs 50 per m square, find the cost of plastering.

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An Important Question of M.L Aggarwal book of class 10 Based on Mensuration Chapter for ICSE BOARD.
You have asked that How many cubic metres of soil must be dug out to make a well 20 metres deep and 2 metres in diameter and also calculate the cost of plastering.
This is the Question Number 05, Exercise 17.1 of M.L Aggarwal.

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1. (i) Given diameter of the well, d = 2 m

Radius, r = d/2 = 2/2 = 1 m

Depth of the well, h = 20 m

Volume of the well, V = r2h

= (22/7)×12×20

= 62.85 m3

Hence the amount of soil dug out to make the well is 62.85 m3.

(ii)Curved surface area of the well = 2rh

= 2×(22/7)×1×20

= 880/7 m2

Cost of plastering the well per m2 = Rs. 50

Total cost of plastering the well = 50×(880/7)

= Rs. 6285.71

Hence the total cost of plastering is Rs. 6285.71.

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