A rectangular container measuring 76 cm by 54 cm by 28 cm was to be filled with water by two taps, Q and R. Tap Q which fills the tank at a rate of 8 ℓ per minute was first turned on for 2 minutes before Tap R was turned on as well. If the tank was filled to the brim in a total of 6 minutes from the time when Tap Q was first turned on, what is the rate at which Tap R fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 76 x 54 x 28
= 114912 cm
3 1 ℓ = 1000 cm
3 8 ℓ = 8000 cm
3 Volume of water filled by Tap Q
= 8000 x 6
= 48000 cm
3 Volume of water filled by Tap R
= 114912 - 48000
= 66912 cm
3 Rate in which Tap R fills the container
= 66912 ÷ 4
= 16728 cm3/min
16728 mℓ/min
= 16.728 ℓ/min
≈ 16.7 ℓ/min (Correct to 1 decimal place)
Answer(s): 16.7 ℓ/min