question_answer

A 21 m deep well with diameter 6 m is dug and the earth from digging is evenly spread to form a platform\[27\text{ }m\times 11\text{ }m\]. Find the height of the platform. \[\left[ \text{Use}\,\,\pi \text{=}\frac{22}{7} \right]\]

Answer:

Volume of earth taken out after digging the well of height 21 m and diameter 6 m.

\[=\frac{22}{7}\times \frac{6}{2}\times \frac{6}{2}\times 21\]

Let h be the height of the platform formed by the earth dug out.

\[\therefore \]    Volume of platform = Volume of earth dug out

\[27\times 11\times h=594\]

\[h=\frac{594}{27\times 11}\]

\[=2.02\,\,m\approx 2\,\,m\]

\[\therefore \] Height of the platform \[=2\text{ }m\]