Given,

Radius of the circular cylinder (r) = 2/2 m = 1 m

Height of the well (h) = 14 m

We know that,

Volume of the solid circular cylinder = π r2h

= π × 12× 14 …. (i)

And,

The height of the embankment (h) = 40 cm = 0.4 m

Let the width of the embankment be (x) m.

The embankment is a hollow cylinder with external radius = 1 + x and internal radius = 1

Volume of the embankment = π × r2 × h

= π × [(1 + x)2 – (1)2]× 0.4 ….. (ii)

As the well is spread evenly to form embankment then the volumes will be same.

So, on equating equations (i) and (ii), we get

π × 12 × 14 = π × [(1 + x)2 – (1)2] x 0.4

14/0.4 = 1 + x2 + 2x – 1

35 = x2 + 2x

x2 + 2x – 35 = 0

Solving by factorization method, we have

(x + 7) (x – 5) = 0

So, x = 5 m can only be the solution as it’s a positive value.

Therefore, the width of the embankment is 5 m.