A rectangular tank measuring 71 cm by 53 cm by 33 cm was to be filled with water by two taps, T and U. Tap T which fills the tank at a rate of 7 ℓ per minute was first turned on for 4 minutes before Tap U was turned on as well. If the tank was filled to the brim in a total of 5 minutes from the time when Tap T was first turned on, what is the rate at which Tap U fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 71 x 53 x 33
= 124179 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap T
= 7000 x 5
= 35000 cm
3 Volume of water filled by Tap U
= 124179 - 35000
= 89179 cm
3 Rate in which Tap U fills the tank
= 89179 ÷ 1
= 89179 cm3/min
89179 mℓ/min
= 89.179 ℓ/min
≈ 89.2 ℓ/min (Correct to 1 decimal place)
Answer(s): 89.2 ℓ/min