Question

13. A well of radius 7 m is dug to a depth of 12km. Earth taken out of it has been evenly
spread all around to form a circular embankment of width 7 m. Find the height of the
embankment.​

Answer 1

Answer:

As the shape of well is of cylinder

.: Radius of well (r1) = 7 m

Depth of well (h1) = 12 km

=12,000 m

The circular embankment is also of cylindrical shape

.: Width of embankment (d) = 7 m

Radius (r2) = 3.5 m

To Find :- Height of embankment (h2)

$volume \: of \: well(cylinder) = volume \: of \: embankment(cylinder) \\ \pi {r1}^{2} h1 = \pi {r2}^{2} h2 \\ \pi \times \: {7}^{2} \times 12000 = \pi \times {3.5}^{2} \times h2 \\ \pi \times 49 \times 12000 = \pi \times 12.25 \times h2 \\ \pi \times 588000 = \pi \times 12.25 \times h2 \\ 588000 = 12.25 \times h2 - - - - (\pi \: cancel) \\ h2 = \frac{588000}{12.25} \\ h2 = 48000$

.: h2 = 48,000 m = 48 km