A rectangular tank measuring 72 cm by 57 cm by 29 cm was to be filled with water by two taps, K and L. Tap K which fills the tank at a rate of 6 ℓ per minute was first turned on for 4 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 tank
= 72 x 57 x 29
= 119016 cm
3 1 ℓ = 1000 cm
3 6 ℓ = 6000 cm
3 Volume of water filled by Tap K
= 6000 x 6
= 36000 cm
3 Volume of water filled by Tap L
= 119016 - 36000
= 83016 cm
3 Rate in which Tap L fills the tank
= 83016 ÷ 2
= 41508 cm3/min
41508 mℓ/min
= 41.508 ℓ/min
≈ 41.5 ℓ/min (Correct to 1 decimal place)
Answer(s): 41.5 ℓ/min