An empty rectangular container has a capacity of 72 ℓ and a height of 20 cm. At 8 a.m., Tap S is turned on to fill the container at a rate of 7 ℓ per minute for 15 minutes. After 5 minutes, Tap T is turned on to drain water from the container at a rate of 10 ℓ per minute for 7 minutes. What is the height of the water level in the container in the end? Give the answer in 1 decimal place.
1 ℓ = 1000 cm³ 
7 ℓ = 7000 cm³ 
10 ℓ = 10000 cm³ 
72 ℓ = 72000 cm³

Volume of water flowed in from Tap S
= 15 x 7000
= 105000 cm³

Volume of water from drained from Tap T
= 7 x 10000
= 70000 cm³

Volume of water left in the container
= 105000 - 70000
= 35000 cm³

Base area of the container
= 72000 ÷ 20
= 3600 cm² 

Height of water left in the container
= 35000 ÷ 3600
≈ 9.7 cm

Answer(s): 9.7 cm