A rectangular tank measuring 81 cm by 56 cm by 36 cm was to be filled with water by two taps, U and V. Tap U which fills the tank at a rate of 7 ℓ per minute was first turned on for 3 minutes before Tap V was turned on as well. If the tank was filled to the brim in a total of 5 minutes from the time when Tap U was first turned on, what is the rate at which Tap V fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 81 x 56 x 36
= 163296 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap U
= 7000 x 5
= 35000 cm
3 Volume of water filled by Tap V
= 163296 - 35000
= 128296 cm
3 Rate in which Tap V fills the tank
= 128296 ÷ 2
= 64148 cm3/min
64148 mℓ/min
= 64.148 ℓ/min
≈ 64.1 ℓ/min (Correct to 1 decimal place)
Answer(s): 64.1 ℓ/min