An empty rectangular container has a capacity of 30 ℓ and a height of 40 cm. At 9 a.m., Tap M is turned on to fill the container at a rate of 6 ℓ per minute for 16 minutes. After 4 minutes, Tap N is turned on to drain water from the container at a rate of 7 ℓ per minute for 13 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 
7 ℓ = 7000 cm³ 
30 ℓ = 30000 cm³

Volume of water flowed in from Tap M
= 16 x 6000
= 96000 cm³

Volume of water from drained from Tap N
= 13 x 7000
= 91000 cm³

Volume of water left in the container
= 96000 - 91000
= 5000 cm³

Base area of the container
= 30000 ÷ 40
= 750 cm² 

Height of water left in the container
= 5000 ÷ 750
≈ 6.7 cm

Answer(s): 6.7 cm