The figure is not drawn to scale. Tank N measuring 48 cm by 47 cm by 20 cm contained 33.56 ℓ of water. Tank P measuring 40 cm by 25 cm by 32 cm contained 20 ℓ of water. Justin poured some water from Tank N into Tank P without spilling and the water level of Tank P rose to 31 cm. What was the height of water level left in Tank N?
1 ℓ = 1000 cm³
20 ℓ = 20000 cm³
33.56 ℓ = 33.56 x 1000 = 33560 cm³

Height of water in Tank P at first
= 20000 ÷ 40 ÷ 25
= 20 cm

Increase in the height of water in Tank P
= 31 - 20
= 11 cm

Volume of water poured into Tank P
= 40 x 25 x 11
= 11000 cm³ 

Volume of water left in Tank N
= 33560 - 11000
= 22560 cm³ 

Height of water left in Tank N
= 22560 ÷ 48 ÷ 47
= 10 cm

Answer(s): 10 cm