A rectangular tank measuring 86 cm by 50 cm by 39 cm was to be filled with water by two taps, H and J. Tap H which fills the tank at a rate of 8 ℓ per minute was first turned on for 2 minutes before Tap J was turned on as well. If the tank was filled to the brim in a total of 6 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
= 86 x 50 x 39
= 167700 cm
3 1 ℓ = 1000 cm
3 8 ℓ = 8000 cm
3 Volume of water filled by Tap H
= 8000 x 6
= 48000 cm
3 Volume of water filled by Tap J
= 167700 - 48000
= 119700 cm
3 Rate in which Tap J fills the tank
= 119700 ÷ 4
= 29925 cm3/min
29925 mℓ/min
= 29.925 ℓ/min
≈ 29.9 ℓ/min (Correct to 1 decimal place)
Answer(s): 29.9 ℓ/min