Given: Length(L) of rectangular piece of ground = 80 m Breadth(B) of rectangular piece of ground = 36 m Length(L) of pit = 40 m Breadth(B) of pit = 18 m Height(H) of pit = 12 m Formula used: Volume of earth taken out = volume of pit = L × B × H Area of rectangle = L × B Calculation: According to the question, Volume of the pit = L × B × H ⇒ 40 m × 18 m × 12 m ⇒ 8640 m3 Area of rectangular piece of ground = L × B ⇒ 80 m × 36 m ⇒ 2880 m2 Area of the base of pit = L × B ⇒ 40 m × 18 m ⇒ 720 m2 Area of remaining portion of rectangular ground = Area of rectangular ground –Area of the base of pit. ⇒ 2880 – 720 ⇒ 2160 m2 Now, the height of the level of remaining part of the ground = volume of pit/area of remaining portion of the rectangular ground ⇒ 8640/2160 ⇒ 4 m ∴ The height of the land is 4 m. Shortcut Trick Height of pit = volume of pit/(area of ground – area of the base pit) ⇒ (40 × 18 × 12)/(80 × 36 – 40 × 18) ⇒ 4 m. ∴ The height of the land is 4 m.