A rectangular container measuring 77 cm by 60 cm by 29 cm was to be filled with water by two taps, Q and R. Tap Q which fills the tank at a rate of 9 ℓ per minute was first turned on for 3 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
= 77 x 60 x 29
= 133980 cm
3 1 ℓ = 1000 cm
3 9 ℓ = 9000 cm
3 Volume of water filled by Tap Q
= 9000 x 6
= 54000 cm
3 Volume of water filled by Tap R
= 133980 - 54000
= 79980 cm
3 Rate in which Tap R fills the container
= 79980 ÷ 3
= 26660 cm3/min
26660 mℓ/min
= 26.66 ℓ/min
≈ 26.7 ℓ/min (Correct to 1 decimal place)
Answer(s): 26.7 ℓ/min