In order to fix an electric pole along a roadside, a pit with dimensions $50$ cm $\times$ $50$ cm is dug with the help of a spade. The pit is prepared by removing earth by $250$ strokes of spade. If one stroke of spade removes $500$ cu. cm of earth, then what is the depth of the pit?

A conical pit is dug into the earth up to the depth of 12 m. It is then closed with a lid of diameter 7m which exactly fitted on it. Find the volume of petrol that can be filled in the conical pit.

The dimensions of a field 15 m by 12 m. A pit 7.5 M long 6 metre wide and 1.5 m Deep is dug at one corner off the field, the earth removed is evenly spread over the remaining area of the field calculate the rise in the level of the field.