A rectangular tank measuring 82 cm by 60 cm by 38 cm was to be filled with water by two taps, X and Y. Tap X which fills the tank at a rate of 8 ℓ per minute was first turned on for 4 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 tank
= 82 x 60 x 38
= 186960 cm
3 1 ℓ = 1000 cm
3 8 ℓ = 8000 cm
3 Volume of water filled by Tap X
= 8000 x 6
= 48000 cm
3 Volume of water filled by Tap Y
= 186960 - 48000
= 138960 cm
3 Rate in which Tap Y fills the tank
= 138960 ÷ 2
= 69480 cm3/min
69480 mℓ/min
= 69.48 ℓ/min
≈ 69.5 ℓ/min (Correct to 1 decimal place)
Answer(s): 69.5 ℓ/min