A rectangular tank measuring 81 cm by 52 cm by 34 cm was to be filled with water by two taps, Z and A. Tap Z which fills the tank at a rate of 8 ℓ per minute was first turned on for 3 minutes before Tap A was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap Z was first turned on, what is the rate at which Tap A fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 81 x 52 x 34
= 143208 cm
3 1 ℓ = 1000 cm
3 8 ℓ = 8000 cm
3 Volume of water filled by Tap Z
= 8000 x 7
= 56000 cm
3 Volume of water filled by Tap A
= 143208 - 56000
= 87208 cm
3 Rate in which Tap A fills the tank
= 87208 ÷ 4
= 21802 cm3/min
21802 mℓ/min
= 21.802 ℓ/min
≈ 21.8 ℓ/min (Correct to 1 decimal place)
Answer(s): 21.8 ℓ/min