A rectangular container measuring 70 cm by 60 cm by 39 cm was to be filled with water by two taps, F and G. Tap F which fills the tank at a rate of 7 ℓ per minute was first turned on for 4 minutes before Tap G was turned on as well. If the tank was filled to the brim in a total of 5 minutes from the time when Tap F was first turned on, what is the rate at which Tap G fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 70 x 60 x 39
= 163800 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap F
= 7000 x 5
= 35000 cm
3 Volume of water filled by Tap G
= 163800 - 35000
= 128800 cm
3 Rate in which Tap G fills the container
= 128800 ÷ 1
= 128800 cm3/min
128800 mℓ/min
= 128.8 ℓ/min
≈ 128.8 ℓ/min (Correct to 1 decimal place)
Answer(s): 128.8 ℓ/min