A rectangular tank measuring 74 cm by 60 cm by 31 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 4 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
= 74 x 60 x 31
= 137640 cm
3 1 ℓ = 1000 cm
3 6 ℓ = 6000 cm
3 Volume of water filled by Tap D
= 6000 x 6
= 36000 cm
3 Volume of water filled by Tap E
= 137640 - 36000
= 101640 cm
3 Rate in which Tap E fills the tank
= 101640 ÷ 2
= 50820 cm3/min
50820 mℓ/min
= 50.82 ℓ/min
≈ 50.8 ℓ/min (Correct to 1 decimal place)
Answer(s): 50.8 ℓ/min