The figure is not drawn to scale. Tank Z measuring 54 cm by 45 cm by 25 cm contained 17.88 ℓ of water. Tank A measuring 40 cm by 34 cm by 34 cm contained 34 ℓ of water. Peter poured some water from Tank Z into Tank A without spilling and the water level of Tank A rose to 31 cm. What was the height of water level left in Tank Z?
1 ℓ = 1000 cm³
34 ℓ = 34000 cm³
17.88 ℓ = 17.88 x 1000 = 17880 cm³

Height of water in Tank A at first
= 34000 ÷ 40 ÷ 34
= 25 cm

Increase in the height of water in Tank A
= 31 - 25
= 6 cm

Volume of water poured into Tank A
= 40 x 34 x 6
= 8160 cm³ 

Volume of water left in Tank Z
= 17880 - 8160
= 9720 cm³ 

Height of water left in Tank Z
= 9720 ÷ 54 ÷ 45
= 4 cm

Answer(s): 4 cm