A rectangular tank measuring 74 cm by 60 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 8 ℓ per minute was first turned on for 4 minutes before Tap P was turned on as well. If the tank was filled to the brim in a total of 5 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 tank
= 74 x 60 x 36
= 159840 cm
3 1 ℓ = 1000 cm
3 8 ℓ = 8000 cm
3 Volume of water filled by Tap N
= 8000 x 5
= 40000 cm
3 Volume of water filled by Tap P
= 159840 - 40000
= 119840 cm
3 Rate in which Tap P fills the tank
= 119840 ÷ 1
= 119840 cm3/min
119840 mℓ/min
= 119.84 ℓ/min
≈ 119.8 ℓ/min (Correct to 1 decimal place)
Answer(s): 119.8 ℓ/min