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Surface Areas and Volumes
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30/06/2021 1:11 pm
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A 20 m deep well with diameter 7 m is dug and the earth from digging is evenly spread out to form a platform 22 m by 14 m. Find the height of the platform.
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30/06/2021 1:12 pm
It is given that the shape of the well is in the shape of a cylinder with a diameter of 7 m
Radius = 7/2 m
Depth (h) = 20 m
∴ Volume of Cylinder = π×r2×h
= 22×7×5 m3
Let the height of the platform = H
Volume of soil from well (cylinder) = Volume of soil used to make such platform
π×r2×h = Area of platform × Height of the platform
We know that the dimension of the platform is = 22×14
Area of platform = 22 × 14 m2
∴ π×r2×h = 22 × 14 × H
H = 2.5 m