Question

How many cubic metres of earth must be dug out to sink a well which is 20m Deep and has a diameter of 7metres ?if the earth so dug out is spread over a rectangular plot 28m by 11m what is the height of the platform so formed ?

Answer 1

Volume=$\pi r^{2}h$

22/7*7/2*20*7/2=770m³

Second part

Volume of cuboid= l*b*h

28*11*h=770

h=2.5m