The figure is not drawn to scale. Tank Q measuring 55 cm by 47 cm by 18 cm contained 38.85 ℓ of water. Tank R measuring 40 cm by 25 cm by 33 cm contained 18 ℓ of water. Archie 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
18 ℓ = 18000 cm³
38.85 ℓ = 38.85 x 1000 = 38850 cm³

Height of water in Tank R at first
= 18000 ÷ 40 ÷ 25
= 18 cm

Increase in the height of water in Tank R
= 31 - 18
= 13 cm

Volume of water poured into Tank R
= 40 x 25 x 13
= 13000 cm³ 

Volume of water left in Tank Q
= 38850 - 13000
= 25850 cm³ 

Height of water left in Tank Q
= 25850 ÷ 55 ÷ 47
= 10 cm

Answer(s): 10 cm