Question

A rectangular field is 120m x 60m. A tank 25m x 8m x 4m is dug in the field. The earth taken out is spread evenly over the remaining area of the field. How much is the level the field raised
if on digging, the volume of the earth is increased by 1/20 of its volume.
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Answer 1

For example:

area of rectangle = 15 * 10 = 150 m2

area of square pit = 5*5 = 25 m2

remaining area = 150-25 = 125 m2

volume of sand dug out = 5*5*1 = 25 m3

therefore 25 m3 we have to spread on 125 m2

this implies rise in the level of field = 25/125 = 1/5 = 0.2 m