A well with 14 m diameter is dug 8 m deep. The earth taken out of it has been evenly spread all around it to a width of 21 m to form an embankment. Find the height of the embankment.


Given,


Diameter of well = 14 m


So, radius of well =


Depth of well = 8 m


Width of embankment = 21 m


So outer radius R = 21+7 = 28 m


Let height of embankment = H m


So, volume of earth in embankment = volume of earth dug out


= π(R2-r2) ×H = πr2h


= π (282 – 72) ×H = π ×49×8


= H =


20