An empty rectangular container has a capacity of 91 ℓ and a height of 130 cm. At 6 a.m., Tap N is turned on to fill the container at a rate of 6 ℓ per minute for 17 minutes. After 9 minutes, Tap P is turned on to drain water from the container at a rate of 3 ℓ per minute for 30 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 
6 ℓ = 6000 cm³ 
3 ℓ = 3000 cm³ 
91 ℓ = 91000 cm³

Volume of water flowed in from Tap N
= 17 x 6000
= 102000 cm³

Volume of water from drained from Tap P
= 30 x 3000
= 90000 cm³

Volume of water left in the container
= 102000 - 90000
= 12000 cm³

Base area of the container
= 91000 ÷ 130
= 700 cm² 

Height of water left in the container
= 12000 ÷ 700
≈ 17.1 cm

Answer(s): 17.1 cm