A rectangular container measuring 80 cm by 60 cm by 36 cm was to be filled with water by two taps, B and C. Tap B which fills the tank at a rate of 6 ℓ per minute was first turned on for 3 minutes before Tap C was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap B was first turned on, what is the rate at which Tap C fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 80 x 60 x 36
= 172800 cm
3 1 ℓ = 1000 cm
3 6 ℓ = 6000 cm
3 Volume of water filled by Tap B
= 6000 x 7
= 42000 cm
3 Volume of water filled by Tap C
= 172800 - 42000
= 130800 cm
3 Rate in which Tap C fills the container
= 130800 ÷ 4
= 32700 cm3/min
32700 mℓ/min
= 32.7 ℓ/min
≈ 32.7 ℓ/min (Correct to 1 decimal place)
Answer(s): 32.7 ℓ/min