A rectangular container measuring 90 cm by 56 cm by 31 cm was to be filled with water by two taps, T and U. Tap T which fills the tank at a rate of 9 ℓ per minute was first turned on for 2 minutes before Tap U was turned on as well. If the tank was filled to the brim in a total of 6 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 container
= 90 x 56 x 31
= 156240 cm
3 1 ℓ = 1000 cm
3 9 ℓ = 9000 cm
3 Volume of water filled by Tap T
= 9000 x 6
= 54000 cm
3 Volume of water filled by Tap U
= 156240 - 54000
= 102240 cm
3 Rate in which Tap U fills the container
= 102240 ÷ 4
= 25560 cm3/min
25560 mℓ/min
= 25.56 ℓ/min
≈ 25.6 ℓ/min (Correct to 1 decimal place)
Answer(s): 25.6 ℓ/min