The figure is not drawn to scale. Y and Z are two containers. The base area of Y is 12 cm² while the base area of Z is 48 cm². Container Y and Z contained some water and the height of the water level in Container Y was 52 cm as shown. Dan then poured some water from Container Y into Container Z. After that, the height of the water level in both tanks became 21 cm. What was the height of the water level in Container Z at first?
Change in the water level of Container Y
= 52 - 21
= 31 cm

Volume of water poured in the Container Z
= 12 x 31
= 372 cm³ 

Height increase in Container Z
= 372 ÷ 48
= 7.75 cm

Original height of the water in Container Z
= 21 - 7.75
= 13.25 cm

Answer(s): 13.25 cm