A rectangular tank measuring 83 cm by 51 cm by 36 cm was to be filled with water by two taps, P and Q. Tap P which fills the tank at a rate of 7 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 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 tank
= 83 x 51 x 36
= 152388 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap P
= 7000 x 5
= 35000 cm
3 Volume of water filled by Tap Q
= 152388 - 35000
= 117388 cm
3 Rate in which Tap Q fills the tank
= 117388 ÷ 2
= 58694 cm3/min
58694 mℓ/min
= 58.694 ℓ/min
≈ 58.7 ℓ/min (Correct to 1 decimal place)
Answer(s): 58.7 ℓ/min