A rectangular container measuring 82 cm by 51 cm by 22 cm was to be filled with water by two taps, H and J. Tap H which fills the tank at a rate of 6 ℓ per minute was first turned on for 3 minutes before Tap J was turned on as well. If the tank was filled to the brim in a total of 7 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 container
= 82 x 51 x 22
= 92004 cm
3 1 ℓ = 1000 cm
3 6 ℓ = 6000 cm
3 Volume of water filled by Tap H
= 6000 x 7
= 42000 cm
3 Volume of water filled by Tap J
= 92004 - 42000
= 50004 cm
3 Rate in which Tap J fills the container
= 50004 ÷ 4
= 12501 cm3/min
12501 mℓ/min
= 12.501 ℓ/min
≈ 12.5 ℓ/min (Correct to 1 decimal place)
Answer(s): 12.5 ℓ/min