The figure is not drawn to scale. P and Q are two containers. The base area of P is 20 cm² while the base area of Q is 28 cm². Container P and Q contained some water and the height of the water level in Container P was 50 cm as shown. Dan then poured some water from Container P into Container Q. After that, the height of the water level in both tanks became 29 cm. What was the height of the water level in Container Q at first?
Change in the water level of Container P
= 50 - 29
= 21 cm

Volume of water poured in the Container Q
= 20 x 21
= 420 cm³ 

Height increase in Container Q
= 420 ÷ 28
= 15 cm

Original height of the water in Container Q
= 29 - 15
= 14 cm

Answer(s): 14 cm