A rectangular container measuring 73 cm by 57 cm by 40 cm was to be filled with water by two taps, N and P. Tap N which fills the tank at a rate of 9 ℓ per minute was first turned on for 2 minutes before Tap P was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap N was first turned on, what is the rate at which Tap P fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 73 x 57 x 40
= 166440 cm
3 1 ℓ = 1000 cm
3 9 ℓ = 9000 cm
3 Volume of water filled by Tap N
= 9000 x 7
= 63000 cm
3 Volume of water filled by Tap P
= 166440 - 63000
= 103440 cm
3 Rate in which Tap P fills the container
= 103440 ÷ 5
= 20688 cm3/min
20688 mℓ/min
= 20.688 ℓ/min
≈ 20.7 ℓ/min (Correct to 1 decimal place)
Answer(s): 20.7 ℓ/min