A rectangular container measuring 84 cm by 50 cm by 28 cm was to be filled with water by two taps, W and X. Tap W which fills the tank at a rate of 7 ℓ per minute was first turned on for 4 minutes before Tap X was turned on as well. If the tank was filled to the brim in a total of 5 minutes from the time when Tap W was first turned on, what is the rate at which Tap X fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 84 x 50 x 28
= 117600 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap W
= 7000 x 5
= 35000 cm
3 Volume of water filled by Tap X
= 117600 - 35000
= 82600 cm
3 Rate in which Tap X fills the container
= 82600 ÷ 1
= 82600 cm3/min
82600 mℓ/min
= 82.6 ℓ/min
≈ 82.6 ℓ/min (Correct to 1 decimal place)
Answer(s): 82.6 ℓ/min