Container T and U are identical containers with the same base area and height. Container T is filled to the brim with water while Container U is empty. After 217 cm³ of water from Container T is poured into Container U, the depth of water in Container U is ¹₂ the depth of water in Container T. If the height of Container U is 21 cm, what is the base area of Container U?
The depth of water is proportional to the volume of water.

After water from Container T is poured into Container U:

Volume of water in Container T : Volume of water in Container U
 2 : 1

1 u = 217

Total volume of Container U
= 2 u + 1 u
= 3 u
= 3 x 217
= 651 cm³

Base area of Container U
= 651 ÷ 21
= 31 cm²

Answer(s): 31 cm²