Question

In the middle of a rectangular field measuring 30m × 20m, a well of 7 m diameter and 10 m depth is dug. The earth so removed is evenly spread over the remaining part of the field. Find the height through which the level of the field is raised.

Answer 1

Let r  m be the radius and h m be the depth of the well that is dug.
Volume of the well = `pi` ​r²h = `22/7` × (3.5 m)² × (10 m) = 385 m³
Volume of the well = Volume of the rectangular field
Volume of the rectangular field = 385 m³ = 30 m × 20 m × height
\[\text{ Height }= \frac{385 {m}^3}{30m \times 20m} = 0 . 641 m = 64 . 1 cm\]
Hence, the height through which the level of the field is raised is 64.1 cm.