A rectangular container measuring 85 cm by 53 cm by 36 cm was to be filled with water by two taps, N and P. Tap N which fills the tank at a rate of 5 ℓ per minute was first turned on for 3 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
= 85 x 53 x 36
= 162180 cm
3 1 ℓ = 1000 cm
3 5 ℓ = 5000 cm
3 Volume of water filled by Tap N
= 5000 x 7
= 35000 cm
3 Volume of water filled by Tap P
= 162180 - 35000
= 127180 cm
3 Rate in which Tap P fills the container
= 127180 ÷ 4
= 31795 cm3/min
31795 mℓ/min
= 31.795 ℓ/min
≈ 31.8 ℓ/min (Correct to 1 decimal place)
Answer(s): 31.8 ℓ/min