In the middle of a rectangular field measuring 30m × 20m, a well of 7 m diameter and 10 m depth is dug.

Let r  m be the radius and h m be the depth of the well that is dug.

Volume of the well $=\pi r^{2} h=$$\frac{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

Hence, the height through which the level of the field is raised is 64.1 cm.