A rectangular container measuring 83 cm by 58 cm by 20 cm was to be filled with water by two taps, L and M. Tap L which fills the tank at a rate of 7 ℓ per minute was first turned on for 2 minutes before Tap M was turned on as well. If the tank was filled to the brim in a total of 6 minutes from the time when Tap L was first turned on, what is the rate at which Tap M fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 83 x 58 x 20
= 96280 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap L
= 7000 x 6
= 42000 cm
3 Volume of water filled by Tap M
= 96280 - 42000
= 54280 cm
3 Rate in which Tap M fills the container
= 54280 ÷ 4
= 13570 cm3/min
13570 mℓ/min
= 13.57 ℓ/min
≈ 13.6 ℓ/min (Correct to 1 decimal place)
Answer(s): 13.6 ℓ/min