A rectangular container measuring 90 cm by 57 cm by 24 cm was to be filled with water by two taps, P and Q. Tap P which fills the tank at a rate of 6 ℓ per minute was first turned on for 4 minutes before Tap Q was turned on as well. If the tank was filled to the brim in a total of 5 minutes from the time when Tap P was first turned on, what is the rate at which Tap Q fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 90 x 57 x 24
= 123120 cm
3 1 ℓ = 1000 cm
3 6 ℓ = 6000 cm
3 Volume of water filled by Tap P
= 6000 x 5
= 30000 cm
3 Volume of water filled by Tap Q
= 123120 - 30000
= 93120 cm
3 Rate in which Tap Q fills the container
= 93120 ÷ 1
= 93120 cm3/min
93120 mℓ/min
= 93.12 ℓ/min
≈ 93.1 ℓ/min (Correct to 1 decimal place)
Answer(s): 93.1 ℓ/min