A rectangular tank measuring 71 cm by 60 cm by 28 cm was to be filled with water by two taps, L and M. Tap L which fills the tank at a rate of 5 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 7 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 tank
= 71 x 60 x 28
= 119280 cm
3 1 ℓ = 1000 cm
3 5 ℓ = 5000 cm
3 Volume of water filled by Tap L
= 5000 x 7
= 35000 cm
3 Volume of water filled by Tap M
= 119280 - 35000
= 84280 cm
3 Rate in which Tap M fills the tank
= 84280 ÷ 5
= 16856 cm3/min
16856 mℓ/min
= 16.856 ℓ/min
≈ 16.9 ℓ/min (Correct to 1 decimal place)
Answer(s): 16.9 ℓ/min