# A 20 m deep well with diameter 7 m is dug and the earth from digging is evenly spread out to form a

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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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Radius of well, ‘r’ = 3.5 m.

Height of well, h = 20 m.

(i) Volume of soil dug out of well, V = πr2h(∵ cylinder sphere)

= 770m3

(ii) Length of platform, l = 22 m.

Height, h = ?

Volume of Platform, V= l × b × h (∵ Cuboid)

= 22 × 14 × h

∴ Volume of Platform = Volume of soil dug out of well.

∴ Height of platform is 2.5 m