A rectangular container measuring 82 cm by 50 cm by 36 cm was to be filled with water by two taps, C and D. Tap C which fills the tank at a rate of 5 ℓ per minute was first turned on for 3 minutes before Tap D was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap C was first turned on, what is the rate at which Tap D fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 82 x 50 x 36
= 147600 cm
3 1 ℓ = 1000 cm
3 5 ℓ = 5000 cm
3 Volume of water filled by Tap C
= 5000 x 7
= 35000 cm
3 Volume of water filled by Tap D
= 147600 - 35000
= 112600 cm
3 Rate in which Tap D fills the container
= 112600 ÷ 4
= 28150 cm3/min
28150 mℓ/min
= 28.15 ℓ/min
≈ 28.2 ℓ/min (Correct to 1 decimal place)
Answer(s): 28.2 ℓ/min