A rectangular tank measuring 80 cm by 60 cm by 32 cm was to be filled with water by two taps, H and J. Tap H which fills the tank at a rate of 7 ℓ per minute was first turned on for 4 minutes before Tap J was turned on as well. If the tank was filled to the brim in a total of 5 minutes from the time when Tap H was first turned on, what is the rate at which Tap J fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 80 x 60 x 32
= 153600 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap H
= 7000 x 5
= 35000 cm
3 Volume of water filled by Tap J
= 153600 - 35000
= 118600 cm
3 Rate in which Tap J fills the tank
= 118600 ÷ 1
= 118600 cm3/min
118600 mℓ/min
= 118.6 ℓ/min
≈ 118.6 ℓ/min (Correct to 1 decimal place)
Answer(s): 118.6 ℓ/min