A rectangular tank measuring 90 cm by 52 cm by 38 cm was to be filled with water by two taps, B and C. Tap B which fills the tank at a rate of 5 ℓ per minute was first turned on for 3 minutes before Tap C was turned on as well. If the tank was filled to the brim in a total of 5 minutes from the time when Tap B was first turned on, what is the rate at which Tap C fills the tank? Give your answer in ℓ per minute correct to 1 decimal place.
Total volume of the tank
= 90 x 52 x 38
= 177840 cm
3 1 ℓ = 1000 cm
3 5 ℓ = 5000 cm
3 Volume of water filled by Tap B
= 5000 x 5
= 25000 cm
3 Volume of water filled by Tap C
= 177840 - 25000
= 152840 cm
3 Rate in which Tap C fills the tank
= 152840 ÷ 2
= 76420 cm3/min
76420 mℓ/min
= 76.42 ℓ/min
≈ 76.4 ℓ/min (Correct to 1 decimal place)
Answer(s): 76.4 ℓ/min