A rectangular container measuring 77 cm by 59 cm by 27 cm was to be filled with water by two taps, Z and A. Tap Z which fills the tank at a rate of 9 ℓ per minute was first turned on for 4 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 container
= 77 x 59 x 27
= 122661 cm
3 1 ℓ = 1000 cm
3 9 ℓ = 9000 cm
3 Volume of water filled by Tap Z
= 9000 x 7
= 63000 cm
3 Volume of water filled by Tap A
= 122661 - 63000
= 59661 cm
3 Rate in which Tap A fills the container
= 59661 ÷ 3
= 19887 cm3/min
19887 mℓ/min
= 19.887 ℓ/min
≈ 19.9 ℓ/min (Correct to 1 decimal place)
Answer(s): 19.9 ℓ/min