A rectangular tank measuring 85 cm by 53 cm by 35 cm was to be filled with water by two taps, D and E. Tap D which fills the tank at a rate of 6 ℓ per minute was first turned on for 2 minutes before Tap E was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap D was first turned on, what is the rate at which Tap E fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 85 x 53 x 35
= 157675 cm
3 1 ℓ = 1000 cm
3 6 ℓ = 6000 cm
3 Volume of water filled by Tap D
= 6000 x 7
= 42000 cm
3 Volume of water filled by Tap E
= 157675 - 42000
= 115675 cm
3 Rate in which Tap E fills the tank
= 115675 ÷ 5
= 23135 cm3/min
23135 mℓ/min
= 23.135 ℓ/min
≈ 23.1 ℓ/min (Correct to 1 decimal place)
Answer(s): 23.1 ℓ/min