Question 50

A 15 m deep well with radius 2.8 m is dug and the earth taken out from it is spread evenly to form platform of breadth 8 m and height 1.5 m. What will be the length of the platform? (Take $$\pi = \frac{22}{7}$$)

Solution

Volume of earth is equal to the volume of the well so,

r = 2.8 m

h = 15 m

volume of earth = $$\pi \times r^2 \times h = \frac{22}{7} \times 2.8^2 \times 15 = 369.6 m^3$$

Volume of earth is equal to the volume of platform so,

volume of platform = length $$\times breadth \times height $$

369.6 = $$8 \times 1.5 \times length$$

length = $$\frac{369.6}{12}$$ = 30.8 m

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