Question

A 20 my deep pit with diameter 7 my is dug up and the earth from digging is spread evenly to form a platform 22 m × 14 my. the height of the platform is

Answer 1

2.5 metres

Volume of cylinder = πr^2h

here it is π x 3.5 sqaure x 20 = 769.69

22*14 = 308

769.69 / 308 = 2.5

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.