A rectangular tank measuring 70 cm by 51 cm by 22 cm was to be filled with water by two taps, G and H. Tap G which fills the tank at a rate of 7 ℓ per minute was first turned on for 2 minutes before Tap H was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap G was first turned on, what is the rate at which Tap H fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 70 x 51 x 22
= 78540 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap G
= 7000 x 7
= 49000 cm
3 Volume of water filled by Tap H
= 78540 - 49000
= 29540 cm
3 Rate in which Tap H fills the tank
= 29540 ÷ 5
= 5908 cm3/min
5908 mℓ/min
= 5.908 ℓ/min
≈ 5.9 ℓ/min (Correct to 1 decimal place)
Answer(s): 5.9 ℓ/min