It takes Faucet T 40 minutes to fill a tank measuring 16 cm by 12 cm by 15 cm completely while it takes Faucet B only 10 minutes. How long will it take to completely fill the tank with water if both faucets are turned on at the same time and 3 cubic cubes of edges 3 cm, filled with water, are poured into the tank? Leave the answer in minutes and round off to 2 decimal places.
Time taken by Faucet T to fill the tank:

40 min → 1 tank
1 min → ¹₄₀ tank

Time taken by Faucet B to fill the tank:
10 min → 1 tank
1 min → ¹₁₀ tank

Volume of the tank
= 16 x 12 x 15
= 2880 cm³

Volume of 3 cubic cubes
= 3 x (3 x 3 x 3)
= 81 cm³

Time taken by Faucet T and Faucet B to fill a tank:
1 min → ¹₄₀ + ¹₁₀ =⁵₄₀ = ¹₈ tank

¹₈ tank → 1 min
1 tank → 1 ÷ ¹₈ = 1 x ⁸₁ = 8 min

Remaining volume of the tank to be filled by both faucets 
= 2880 - 81
= 2799 cm³

Time taken to fill the tank
= ²⁷⁹⁹₂₈₈₀ x 8
= 7.775
≈ 7.78 min

Answer(s): 7.78 min