Question

a well is dug 20 m Deep and has a diameter of 7 m . the Earth which is so dug out is spread evenly on a rectangular plot 22 m long and 14m broad . what is the height of platform formed

Answer 1

well
d=7m
r=7/2m
h=20m

platform
L=22m
B=14m
H=?

volume of well=volume of platform
πr²h=L×B×H
22/7×7/2×7/2×20=22×14×H
21560/28=308×H
770=308×H
2.5=H

height of platform is 2.5m

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Answer 2

⇒ Given:- Height (h) of well :- 20m

Diameter (d) :- 7 m

Radius (r) :- 7/2 m

Volume of earth platform :- 22 m by 14m

⇒ To find :- Height of the platform:- ?

⇒ Solution:-

Volume of cylinder of radius 7/2 m and height 20 m

Volume of cylinder :- π(r^2)(h)

= 22/7×(7/2^2)×20 m^3

= 770 m^3

Let the height raised by 22 m × 14 m platform be equal to h metres

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

Hence , the height of the platform is 2.5 m.