A rectangular container measuring 85 cm by 55 cm by 35 cm was to be filled with water by two taps, J and K. Tap J which fills the tank at a rate of 9 ℓ per minute was first turned on for 2 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 container
= 85 x 55 x 35
= 163625 cm
3 1 ℓ = 1000 cm
3 9 ℓ = 9000 cm
3 Volume of water filled by Tap J
= 9000 x 7
= 63000 cm
3 Volume of water filled by Tap K
= 163625 - 63000
= 100625 cm
3 Rate in which Tap K fills the container
= 100625 ÷ 5
= 20125 cm3/min
20125 mℓ/min
= 20.125 ℓ/min
≈ 20.1 ℓ/min (Correct to 1 decimal place)
Answer(s): 20.1 ℓ/min