A rectangular tank measuring 74 cm by 60 cm by 22 cm was to be filled with water by two taps, K and L. Tap K which fills the tank at a rate of 9 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 tank
= 74 x 60 x 22
= 97680 cm
3 1 ℓ = 1000 cm
3 9 ℓ = 9000 cm
3 Volume of water filled by Tap K
= 9000 x 6
= 54000 cm
3 Volume of water filled by Tap L
= 97680 - 54000
= 43680 cm
3 Rate in which Tap L fills the tank
= 43680 ÷ 4
= 10920 cm3/min
10920 mℓ/min
= 10.92 ℓ/min
≈ 10.9 ℓ/min (Correct to 1 decimal place)
Answer(s): 10.9 ℓ/min