The dimensions of the well are
Radius = 5m
Depth = 8.4m
We know that
Volume of the earth dug out = Volume of well = πr2h
By substituting the values
Volume of the earth dug out = (22/7) × (5)2 × 8.4
So we get
Volume of the earth dug out = 660 m2
It is given that
Width of embankment = 7.5m
We know that
External radius of embankment R = 5 + 7.5 = 12.5m
Internal radius of embankment r = 5m
We know that
Area of embankment = π (R2 – r2)
By substituting the values
Area of embankment = (22/7) × (12.52 – 52)
On further calculation
Area of embankment = (22/7) × (156.25 – 25)
So we get
Area of embankment = (22/7) × 131.25 = 412.5 m2
We know that
Volume of embankment = volume of earth dug out = 660m2
So the height of embankment = volume of embankment/ area of embankment
By substituting the values
Height of embankment = 660/ 412.5 = 1.6m
Therefore, the height of the embankment is 1.6m.