Question

A 20m deep well with diameter 7m is dug up and the earth from digging is spread evenly to form a platform 22m x 14m. Determine the height of the platform.
...plzz answer..
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Answer 1

Answer: 17.5m

Step-by-step explanation:- volume of well = volume of plat form spreaded

22/7×7/2×7/2×20 = 22/7× 14×h

770=44×h

770/44=h

17.5=h

Answer 2

Answer

Height of the platform is 2.5 m

Explanation

A 20m deep well with diameter 7m is dug up.

We given that, height of well is 20 m and diameter of the well is 7 m.

Radius = Diamter/2 = 7/2 m

Also, earth from digging is spread evenly to form a platform 22m x 14m.

So, length of platform is 22 m and breadth is 14 m.

According to question,

Volume of cylinder = πr²h

⇒ 22/7 × (7/2)² × 20

⇒ 22/7 × 49/4 × 20

⇒ 770 m³

Let the height of the platform be h m.

Therefore,

Volume of the earth in platform = Volume of the earth taken out of the well

⇒ 22 × 14 × h = 770

⇒ h = 770/22 × 14 m

⇒ h = 5/2 m

⇒ h = 2.5 m