A rectangular tank measuring 85 cm by 57 cm by 28 cm was to be filled with water by two taps, E and F. Tap E which fills the tank at a rate of 7 ℓ per minute was first turned on for 3 minutes before Tap F was turned on as well. If the tank was filled to the brim in a total of 6 minutes from the time when Tap E was first turned on, what is the rate at which Tap F fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 85 x 57 x 28
= 135660 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap E
= 7000 x 6
= 42000 cm
3 Volume of water filled by Tap F
= 135660 - 42000
= 93660 cm
3 Rate in which Tap F fills the tank
= 93660 ÷ 3
= 31220 cm3/min
31220 mℓ/min
= 31.22 ℓ/min
≈ 31.2 ℓ/min (Correct to 1 decimal place)
Answer(s): 31.2 ℓ/min