A tank 40 m long, 30 m broad and 12 m deep is dug in a field 1000 m long and 30 m wide. By how much will the level of the field rise if the earth dug out of the tank is evenly spread over the field?

Answer: Option C

Volume of earth taken out = 40 × 30 × 12 = 14400 m³
Area of rectangular field = 1000 × 30 = 30000 m²
Area of region of tank = 40 × 30 = 1200 m²
Remaining area = 30000 - 1200 = 28800 m²
Increase in height $$=\frac{14400}{28800}=0.5\text{ m}$$