A rectangular container measuring 84 cm by 59 cm by 25 cm was to be filled with water by two taps, A and B. Tap A which fills the tank at a rate of 8 ℓ per minute was first turned on for 4 minutes before Tap B was turned on as well. If the tank was filled to the brim in a total of 5 minutes from the time when Tap A was first turned on, what is the rate at which Tap B fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 84 x 59 x 25
= 123900 cm
3 1 ℓ = 1000 cm
3 8 ℓ = 8000 cm
3 Volume of water filled by Tap A
= 8000 x 5
= 40000 cm
3 Volume of water filled by Tap B
= 123900 - 40000
= 83900 cm
3 Rate in which Tap B fills the container
= 83900 ÷ 1
= 83900 cm3/min
83900 mℓ/min
= 83.9 ℓ/min
≈ 83.9 ℓ/min (Correct to 1 decimal place)
Answer(s): 83.9 ℓ/min