A rectangular container measuring 80 cm by 56 cm by 37 cm was to be filled with water by two taps, C and D. Tap C which fills the tank at a rate of 9 ℓ per minute was first turned on for 2 minutes before Tap D was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap C was first turned on, what is the rate at which Tap D fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 80 x 56 x 37
= 165760 cm
3 1 ℓ = 1000 cm
3 9 ℓ = 9000 cm
3 Volume of water filled by Tap C
= 9000 x 7
= 63000 cm
3 Volume of water filled by Tap D
= 165760 - 63000
= 102760 cm
3 Rate in which Tap D fills the container
= 102760 ÷ 5
= 20552 cm3/min
20552 mℓ/min
= 20.552 ℓ/min
≈ 20.6 ℓ/min (Correct to 1 decimal place)
Answer(s): 20.6 ℓ/min