Question

A 20m deep well of diameter 7 m is dug and the earth got by digging is evenly spread out
to form a rectangular platform of base 22 m x 14m. Find the height of the platform.
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Answer 1

answer - 2.5m

explanation-

here, shape of well is in form of cylinder and shape of platform will be in shape of cuboid.

volume of well = volume of platform

volume of cylinder= volume of cuboid

1. volume of cylinder

diameter = 7m

radius = r = 7/2

height = h = 20m

volume of cylinder= 22/7× (7/2)²× 20

= 770m³

2. volume of cuboid

length= 22m

breadth= 14m

height = h m

volume of cuboid= l×b×h

=22×14× h

now,

volume of cylinder = volume of cuboid

770 = 22× 14× h

h = 770 / 22× 14

h = 2.5 m