A rectangular tank measuring 77 cm by 55 cm by 39 cm was to be filled with water by two taps, H and J. Tap H which fills the tank at a rate of 7 ℓ per minute was first turned on for 3 minutes before Tap J was turned on as well. If the tank was filled to the brim in a total of 6 minutes from the time when Tap H was first turned on, what is the rate at which Tap J fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 77 x 55 x 39
= 165165 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap H
= 7000 x 6
= 42000 cm
3 Volume of water filled by Tap J
= 165165 - 42000
= 123165 cm
3 Rate in which Tap J fills the tank
= 123165 ÷ 3
= 41055 cm3/min
41055 mℓ/min
= 41.055 ℓ/min
≈ 41.1 ℓ/min (Correct to 1 decimal place)
Answer(s): 41.1 ℓ/min