A rectangular tank measuring 75 cm by 53 cm by 21 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 4 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 tank
= 75 x 53 x 21
= 83475 cm
3 1 ℓ = 1000 cm
3 5 ℓ = 5000 cm
3 Volume of water filled by Tap D
= 5000 x 5
= 25000 cm
3 Volume of water filled by Tap E
= 83475 - 25000
= 58475 cm
3 Rate in which Tap E fills the tank
= 58475 ÷ 1
= 58475 cm3/min
58475 mℓ/min
= 58.475 ℓ/min
≈ 58.5 ℓ/min (Correct to 1 decimal place)
Answer(s): 58.5 ℓ/min