Question

how many cubic m of earth must be dug out to sink a well 16 m in depth and 7m in diameters

Answer 1

Vol of mud = Vol of well.

Vol of well=$\pi r^{2} h$
                = $\frac{22}{7} * \frac{7}{2}* \frac{7}{2}*16$
                = 616m³
Therefore, amount of mud to be dug out = 616m³
Hope it helped!
NISHTHA.