How many cubic metre of esrth must be dug out to sink a well which is 20 m deep and has a diameter of 7 meyres. If thr earth so dug out is spread over a rectangular plot 28 cm /11 m. what is the height of platform so formed.
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The well is in form of a cylinder. Since the well is dug out of the earth so the volume of the earth dug out is equal to the volume of the cylindrical well. The dia of the well is 7 meters and the depth is 20 mtrs.
So the volume of earth dug = volume of the well
= pi * r*r*h where r is the radii of the well and h is the depth
= 22/7 * 7/2*7/2*20
= 770 cu. meter.
The same soil is spread over a rectangular area of 28m X 11 m. This causes the level of the plot to rise and thus creating a cuboid. So the volume of the cuboid so formed is equal to the volume of the earth dug as the same earth is spread.
so volume of the cuboid = l * b* h where l = length, b = breadth and h is the height of the cuboid
770 = 28 * 11 *h
h = 770/28*11
h = 2.5 meters
So the volume of earth dug = volume of the well
= pi * r*r*h where r is the radii of the well and h is the depth
= 22/7 * 7/2*7/2*20
= 770 cu. meter.
The same soil is spread over a rectangular area of 28m X 11 m. This causes the level of the plot to rise and thus creating a cuboid. So the volume of the cuboid so formed is equal to the volume of the earth dug as the same earth is spread.
so volume of the cuboid = l * b* h where l = length, b = breadth and h is the height of the cuboid
770 = 28 * 11 *h
h = 770/28*11
h = 2.5 meters
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