Q4 of 32 Page 267

A well of diameter 14 m. is dug 15 m. deep. The earth taken out of it has been spread evenly to form circular embankment of width 7 m. Find the height of the embankment.


Given that, height of cylindrical well(h) is 15 m and diameter(d) is 14 m. And width of circular embankment is 7 m.


⇒ radius(r) of well


⇒ outer radius of Embankment(R1) = (7 + 7) = 14 m


⇒ inner radius(r1) = 7 m


Let the height of the embankment be H.


⇒ vol. of well = vol. of embankment


⇒ πr2h = π(R12-r12)H




⇒ H = 5 cm


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