A rectangular tank measuring 73 cm by 58 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 9 ℓ per minute was first turned on for 3 minutes before Tap Q was turned on as well. If the tank was filled to the brim in a total of 6 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 tank
= 73 x 58 x 24
= 101616 cm
3 1 ℓ = 1000 cm
3 9 ℓ = 9000 cm
3 Volume of water filled by Tap P
= 9000 x 6
= 54000 cm
3 Volume of water filled by Tap Q
= 101616 - 54000
= 47616 cm
3 Rate in which Tap Q fills the tank
= 47616 ÷ 3
= 15872 cm3/min
15872 mℓ/min
= 15.872 ℓ/min
≈ 15.9 ℓ/min (Correct to 1 decimal place)
Answer(s): 15.9 ℓ/min