To fill a tank measuring 40 cm by 30 cm by 50 cm completely, it takes Tap D 6 minutes while it takes Tap E only 14 minutes. How long will it take to completely fill the container with water if both the taps are turned on at the same time and 9 cubic containers of edges 10 cm, filled to the brim with water are poured into the tank?
Volume of the tank 
= 40 x 30 x 50
= 60000 cm³

Volume of 9 containers
= 10 x 10 x 10 x 9
= 9000 mℓ

Remaining volume to be filled by the Tap D and Tap E 
= 60000 - 9000
= 51000 mℓ
= 51000 cm³

Fraction of the tank to be filled
= ⁵¹⁰⁰⁰₆₀₀₀₀
= ¹⁷₂₀

Tap D:
1 tank → 6 min
1 min → ¹₆ tank

Tap E:
1 tank → 14 min
1 min → ¹₁₄ tank

Tap D and Tap E:
1 min → ¹₆ + ¹₁₄ = ⁷₄₂ + ³₄₂ = ⁵₂₁ tank
1 tank → ²¹₅ min

¹⁷₂₀ tank → ²¹₅ x ¹⁷₂₀ = ³⁵⁷₁₀₀ = 3.57 min

Answer(s): 3.57 min