The figure is not drawn to scale. E and F are two containers. The base area of E is 10 cm² while the base area of F is 50 cm². Container E and F contained some water and the height of the water level in Container E was 55 cm as shown. Dan then poured some water from Container E into Container F. After that, the height of the water level in both tanks became 18 cm. What was the height of the water level in Container F at first?
Change in the water level of Container E
= 55 - 18
= 37 cm

Volume of water poured in the Container F
= 10 x 37
= 370 cm³ 

Height increase in Container F
= 370 ÷ 50
= 7.4 cm

Original height of the water in Container F
= 18 - 7.4
= 10.6 cm

Answer(s): 10.6 cm