A 20m deep well with diameter 7m is dug and the earth from digging is evenly spread out to form a platform 22m by14m.Find the heinght of the platform.

the well will be in the cylindrical shape. its radius r =7/2m

and height h =20 m.

the volume of the earth dug out =

area of the platform= 22*14 m square

let the height of the platform be H m.

volume of the platform = volume of the earth dug out


H=35/14=5/2=2.5 m.

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Clearly the well is in the form of a cylinder with r = 7/2 m , h = 20 m

Thus, volume of the cylinder = pi x r2 x h = 22/7 x 7/2 x 7/2 x 20 = 11 x 7 x 10 = 770 m3

Again, The dimensions of the rectangle is 22m x 14 m

so let the height of the cuboid so formed be h

so, 22 x 14 x h = 770

=> h = 5/2 = 2.5 m Ans...

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