The figure is not drawn to scale. Tank Q measuring 55 cm by 42 cm by 15 cm contained 39.1 ℓ of water. Tank R measuring 40 cm by 25 cm by 35 cm contained 15 ℓ of water. Nick poured some water from Tank Q into Tank R without spilling and the water level of Tank R rose to 31 cm. What was the height of water level left in Tank Q?
1 ℓ = 1000 cm³
15 ℓ = 15000 cm³
39.1 ℓ = 39.1 x 1000 = 39100 cm³

Height of water in Tank R at first
= 15000 ÷ 40 ÷ 25
= 15 cm

Increase in the height of water in Tank R
= 31 - 15
= 16 cm

Volume of water poured into Tank R
= 40 x 25 x 16
= 16000 cm³ 

Volume of water left in Tank Q
= 39100 - 16000
= 23100 cm³ 

Height of water left in Tank Q
= 23100 ÷ 55 ÷ 42
= 10 cm

Answer(s): 10 cm