A rectangular container measuring 70 cm by 54 cm by 32 cm was to be filled with water by two taps, Y and Z. Tap Y which fills the tank at a rate of 7 ℓ per minute was first turned on for 4 minutes before Tap Z was turned on as well. If the tank was filled to the brim in a total of 6 minutes from the time when Tap Y was first turned on, what is the rate at which Tap Z fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 70 x 54 x 32
= 120960 cm³ 

1 ℓ = 1000 cm³ 
7 ℓ = 7000 cm³ 

Volume of water filled by Tap Y
= 7000 x 6
= 42000 cm³

Volume of water filled by Tap Z
= 120960 - 42000
= 78960 cm³ 

Rate in which Tap Z fills the container
= 78960 ÷ 2
39480 mℓ/min
= 39.48 ℓ/min
≈ 39.5 ℓ/min (Correct to 1 decimal place)

Answer(s): 39.5 ℓ/min