A rectangular container measuring 78 cm by 56 cm by 31 cm was to be filled with water by two taps, K and L. Tap K which fills the tank at a rate of 5 ℓ per minute was first turned on for 2 minutes before Tap L was turned on as well. If the tank was filled to the brim in a total of 6 minutes from the time when Tap K was first turned on, what is the rate at which Tap L fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 78 x 56 x 31
= 135408 cm
3 1 ℓ = 1000 cm
3 5 ℓ = 5000 cm
3 Volume of water filled by Tap K
= 5000 x 6
= 30000 cm
3 Volume of water filled by Tap L
= 135408 - 30000
= 105408 cm
3 Rate in which Tap L fills the container
= 105408 ÷ 4
= 26352 cm3/min
26352 mℓ/min
= 26.352 ℓ/min
≈ 26.4 ℓ/min (Correct to 1 decimal place)
Answer(s): 26.4 ℓ/min