3. A 20 m deep well with diameter 7 m is dug and the earth from digging in evenly spread
out to form a platform 22m×14m

2 thoughts on “<br />3. A 20 m deep well with diameter 7 m is dug and the earth from digging in evenly spread<br />out to form a platform 22m×14m”

1. Step-by-step explanation:

   22*14*h=22/7*7/2*7/2*20

   h=22/7*7/2*7/2*20*1/22*1/14

   h=20/8=2.5m

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2. Answer:

   The shape of the well will be cylindrical as shown in the figure below:

   Given:

   Depth (h) of well =20 m

   Radius (r) of circular end of well =

   2

   7

   m

   Area of platform = Length x Breadth =22×14m

   2

   Assume height of the platform =H

   The volume of soil dug from the well will be equal to the volume of soil scattered on the platform.

   Volume of soil from well = Volume of soil used to make such platform

   ⟹πr

   2

   h = Area of platform x Height of platform

   ⟹π×(

   2

   7

   )

   2

   ×20=22×14×H

   H=

   7

   22

   ×

   4

   49

   ×

   22×14

   20

   H=

   2

   5

   =2.5m

   Hence, the height of such a platform will be 2.5 m.

   solution

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