A rectangular tank measuring 73 cm by 60 cm by 27 cm was to be filled with water by two taps, C and D. Tap C which fills the tank at a rate of 8 ℓ per minute was first turned on for 3 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 tank
= 73 x 60 x 27
= 118260 cm
3 1 ℓ = 1000 cm
3 8 ℓ = 8000 cm
3 Volume of water filled by Tap C
= 8000 x 7
= 56000 cm
3 Volume of water filled by Tap D
= 118260 - 56000
= 62260 cm
3 Rate in which Tap D fills the tank
= 62260 ÷ 4
= 15565 cm3/min
15565 mℓ/min
= 15.565 ℓ/min
≈ 15.6 ℓ/min (Correct to 1 decimal place)
Answer(s): 15.6 ℓ/min