A well is dug 20 m deep and it has a diameter of 7 m.

Question:

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?

Solution:

Height of the well = h m = 20 m

Diameter of the well = d m =7 m

Radius of the well = r m = 3.5 m

Volume of the well = πr2h$\frac{22}{7}(3.5)^{2}(20) \mathrm{m}^{3}=770 \mathrm{~m}^{3}$

Volume of the well = Volume of the rectangular plot

Length of the rectangular plot = 22 m

Breadth of the rectangular plot =14 m

Volume of the rectangular plot = 770 m3 = (Length×">×× Breadth ×">××Height) of the rectangular plot

Height $=\frac{770}{22 \times 14}=2.5 \mathrm{~m}$

Thus, the height of the platform is 2.5 m.

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