A rectangular container measuring 78 cm by 55 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 7 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 5 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 container
= 78 x 55 x 39
= 167310 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap D
= 7000 x 5
= 35000 cm
3 Volume of water filled by Tap E
= 167310 - 35000
= 132310 cm
3 Rate in which Tap E fills the container
= 132310 ÷ 2
= 66155 cm3/min
66155 mℓ/min
= 66.155 ℓ/min
≈ 66.2 ℓ/min (Correct to 1 decimal place)
Answer(s): 66.2 ℓ/min