A rectangular container measuring 85 cm by 54 cm by 23 cm was to be filled with water by two taps, X and Y. Tap X which fills the tank at a rate of 6 ℓ per minute was first turned on for 3 minutes before Tap Y was turned on as well. If the tank was filled to the brim in a total of 6 minutes from the time when Tap X was first turned on, what is the rate at which Tap Y fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 85 x 54 x 23
= 105570 cm
3 1 ℓ = 1000 cm
3 6 ℓ = 6000 cm
3 Volume of water filled by Tap X
= 6000 x 6
= 36000 cm
3 Volume of water filled by Tap Y
= 105570 - 36000
= 69570 cm
3 Rate in which Tap Y fills the container
= 69570 ÷ 3
= 23190 cm3/min
23190 mℓ/min
= 23.19 ℓ/min
≈ 23.2 ℓ/min (Correct to 1 decimal place)
Answer(s): 23.2 ℓ/min