A rectangular tank measuring 73 cm by 60 cm by 36 cm was to be filled with water by two taps, M and N. Tap M which fills the tank at a rate of 5 ℓ per minute was first turned on for 2 minutes before Tap N was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap M was first turned on, what is the rate at which Tap N fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 73 x 60 x 36
= 157680 cm
3 1 ℓ = 1000 cm
3 5 ℓ = 5000 cm
3 Volume of water filled by Tap M
= 5000 x 7
= 35000 cm
3 Volume of water filled by Tap N
= 157680 - 35000
= 122680 cm
3 Rate in which Tap N fills the tank
= 122680 ÷ 5
= 24536 cm3/min
24536 mℓ/min
= 24.536 ℓ/min
≈ 24.5 ℓ/min (Correct to 1 decimal place)
Answer(s): 24.5 ℓ/min