We have,
Diameter of well = 7 m
Radius of well = d/2 = 7/2 = 3.5m
Depth of well = 10 m
Volume of well = πr2h
= 22/7 × 3.5 × 3.5 × 10
= 385 m3
Area of embankment field = 30 × 20 – 22/7 × 7/2 × 7/2
= 600 – 38.5 = 561.5 m2
Volume of well =Area of embankment field × height of embankment
385 = 561.5 × h
h = 385/561.5
= 0.6856m
= 68.56 cm
∴ Height of embankment is 68.56 cm