To fill a tank measuring 40 cm by 20 cm by 40 cm completely, it takes Tap G 8 minutes while it takes Tap H only 18 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 6 cubic containers of edges 10 cm, filled to the brim with water are poured into the tank?
Volume of the tank 
= 40 x 20 x 40
= 32000 cm³

Volume of 6 containers
= 10 x 10 x 10 x 6
= 6000 mℓ

Remaining volume to be filled by the Tap G and Tap H 
= 32000 - 6000
= 26000 mℓ
= 26000 cm³

Fraction of the tank to be filled
= ²⁶⁰⁰⁰₃₂₀₀₀
= ¹³₁₆

Tap G:
1 tank → 8 min
1 min → ¹₈ tank

Tap H:
1 tank → 18 min
1 min → ¹₁₈ tank

Tap G and Tap H:
1 min → ¹₈ + ¹₁₈ = ⁹₇₂ + ⁴₇₂ = ¹³₇₂ tank
1 tank → ⁷²₁₃ min

¹³₁₆ tank → ⁷²₁₃ x ¹³₁₆ = ⁹₂ = 4.5 min

Answer(s): 4.5 min