A rectangular tank measuring 84 cm by 52 cm by 23 cm was to be filled with water by two taps, J and K. Tap J which fills the tank at a rate of 8 ℓ per minute was first turned on for 3 minutes before Tap K was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap J was first turned on, what is the rate at which Tap K fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 84 x 52 x 23
= 100464 cm
3 1 ℓ = 1000 cm
3 8 ℓ = 8000 cm
3 Volume of water filled by Tap J
= 8000 x 7
= 56000 cm
3 Volume of water filled by Tap K
= 100464 - 56000
= 44464 cm
3 Rate in which Tap K fills the tank
= 44464 ÷ 4
= 11116 cm3/min
11116 mℓ/min
= 11.116 ℓ/min
≈ 11.1 ℓ/min (Correct to 1 decimal place)
Answer(s): 11.1 ℓ/min