A rectangular container measuring 77 cm by 55 cm by 28 cm was to be filled with water by two taps, S and T. Tap S which fills the tank at a rate of 9 ℓ per minute was first turned on for 3 minutes before Tap T was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap S was first turned on, what is the rate at which Tap T fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 77 x 55 x 28
= 118580 cm
3 1 ℓ = 1000 cm
3 9 ℓ = 9000 cm
3 Volume of water filled by Tap S
= 9000 x 7
= 63000 cm
3 Volume of water filled by Tap T
= 118580 - 63000
= 55580 cm
3 Rate in which Tap T fills the container
= 55580 ÷ 4
= 13895 cm3/min
13895 mℓ/min
= 13.895 ℓ/min
≈ 13.9 ℓ/min (Correct to 1 decimal place)
Answer(s): 13.9 ℓ/min