Q12 of 45 Page 11

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

Given: Height = 20 m


Diameter = 7 m


Length of plot = 22 m


Breadth of plot = 14 m


To find: The height of platform


Formula Used:


Area of rectangle = Length × Breadth


Volume of cylinder = πr2h


Given,


Depth of well = 20m


Diameter of well = 7 m


Radius of well =


Dimension of rectangular field = 22m × 14m


so,


Amount of earth dug out from well = πr2



=770 m3


when this earth is spread on rectangular field:


⇒ Volume of the well = Volume of rectangular field


⇒ Volume of the well = Area of rectangular field × Height of rectangular field


Then height of platform formed on rectangular field =


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