Q. 13

# A well of diameter 3 m dug 14 m deep the earth was taken out of it has been spread evenly all around it in the shape of a circular ring of width 4 m to form an embarkment. Find the height of embarkment.

Answer :

**Given:** diameter of well = 3 m

Depth of well = 14 m

Width of embankment = 4 m

**To find:** Height of embarkment.

**Formula Used:**

volume of the cylinder = πr^{2}h

**Explanation:**

Height of the well = 14 m

Diameter of the well = 3 m

So, radius =

Let height of embankment be “h” m.

As earth is taken out from the well and has been spread to make a cylindrical embankment,

⇒ Volume of the earth taken out = volume of the well = πr^{2}h

Volume of the earth taken out = πr^{2}h

=

Outer radius of the embankment = R

Area of the embankment = Outer area – Inner area

= πR^{2} -πr^{2}

= π(R^{2} -r^{2})

Height of the embankment =

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