A rectangular tank measuring 78 cm by 59 cm by 37 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 6 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
= 78 x 59 x 37
= 170274 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap U
= 7000 x 6
= 42000 cm
3 Volume of water filled by Tap V
= 170274 - 42000
= 128274 cm
3 Rate in which Tap V fills the tank
= 128274 ÷ 3
= 42758 cm3/min
42758 mℓ/min
= 42.758 ℓ/min
≈ 42.8 ℓ/min (Correct to 1 decimal place)
Answer(s): 42.8 ℓ/min