A rectangular tank measuring 78 cm by 54 cm by 39 cm was to be filled with water by two taps, D and E. Tap D which fills the tank at a rate of 5 ℓ per minute was first turned on for 3 minutes before Tap E was turned on as well. If the tank was filled to the brim in a total of 6 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
= 78 x 54 x 39
= 164268 cm
3 1 ℓ = 1000 cm
3 5 ℓ = 5000 cm
3 Volume of water filled by Tap D
= 5000 x 6
= 30000 cm
3 Volume of water filled by Tap E
= 164268 - 30000
= 134268 cm
3 Rate in which Tap E fills the tank
= 134268 ÷ 3
= 44756 cm3/min
44756 mℓ/min
= 44.756 ℓ/min
≈ 44.8 ℓ/min (Correct to 1 decimal place)
Answer(s): 44.8 ℓ/min