Question

a well is dug 20 meter deep and it has a diameter of 7 m.the earth which is so dug out is spread out on a rectangular plot of 22 m long nd 14 m broad. whats is the height of the platform so formed?

Answer 1

given
well(cylinder shape) dimensions
depth =H =20m
diameter=d=7m
radius =r=d/2=7/2 m
shape of the mud spread out is cuboid
Dimensions
length=l=22m
breadth =b=14m
height = h m

volume of the mud spread out = volume of the mud dug
volume of the cuboid = volume of cylinder
l×b×h= pi*r^2*H
22*14*h=22/7*7/2*7/2*20

h=(22*7*7*20)/(7*2*2*22*14)
after cancellation
h= 5/2
h=2.5 m

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.