Question

if the inner curved surface of the well in part (1) above is to be plastered at the rate of rupees 50 per meter square , find the cost of plastering

Answer 1

Sol:

Depth of the sink = 22.5 m

Diameter of the sink = 7 m

Radius of the sink = 7/2 m

Volume of the earth taken from the sink = πr2h

= 22/7 x 7/2 x 7/2 x 22.5

= 3465 / 4

= 866.25 m3

Inner curved surface area of teh sink = 2πrh

= 2 x 22/7 x 7/2 x 22.5

= 495 m2

Cost of plastering = Rs 3 per m2

Total cost of plastering = 495 x 3 = Rs 1485