A rectangular container measuring 90 cm by 55 cm by 32 cm was to be filled with water by two taps, X and Y. Tap X which fills the tank at a rate of 7 ℓ per minute was first turned on for 3 minutes before Tap Y was turned on as well. If the tank was filled to the brim in a total of 7 minutes from the time when Tap X was first turned on, what is the rate at which Tap Y fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the container
= 90 x 55 x 32
= 158400 cm
3 1 ℓ = 1000 cm
3 7 ℓ = 7000 cm
3 Volume of water filled by Tap X
= 7000 x 7
= 49000 cm
3 Volume of water filled by Tap Y
= 158400 - 49000
= 109400 cm
3 Rate in which Tap Y fills the container
= 109400 ÷ 4
= 27350 cm3/min
27350 mℓ/min
= 27.35 ℓ/min
≈ 27.4 ℓ/min (Correct to 1 decimal place)
Answer(s): 27.4 ℓ/min