A 20m deep well with diameter 7m is dug out and earth from diffing is spread evenly to form a platform 22m *14 m find the height of platform
Answers
volume of earth dug=πr²h=22/7*7/2*7/2*20=770 m³
volume of platform=LBH=22*14*h m³(let h be the height of platform in metres)
volume of earth dug=volume of platform(since same soil which is dug is used to make platform)
770=22*14*h
⇒h=770/22*14
∴h=2.5 m
⇒ 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.