A rectangular container measuring 76 cm by 57 cm by 39 cm was to be filled with water by two taps, M and N. Tap M which fills the tank at a rate of 9 ℓ per minute was first turned on for 3 minutes before Tap N was turned on as well. If the tank was filled to the brim in a total of 6 minutes from the time when Tap M was first turned on, what is the rate at which Tap N fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 76 x 57 x 39
= 168948 cm
3 1 ℓ = 1000 cm
3 9 ℓ = 9000 cm
3 Volume of water filled by Tap M
= 9000 x 6
= 54000 cm
3 Volume of water filled by Tap N
= 168948 - 54000
= 114948 cm
3 Rate in which Tap N fills the container
= 114948 ÷ 3
= 38316 cm3/min
38316 mℓ/min
= 38.316 ℓ/min
≈ 38.3 ℓ/min (Correct to 1 decimal place)
Answer(s): 38.3 ℓ/min