A container holds some water up to a height of 89 cm. When 2 identical plastic cubes are put into the container, the water level rises by 38 cm. One plastic cube is then removed from the tank, replaced by one iron cube. The water level increases to 132 cm.

1. Find the ratio of the volume of 1 plastic cube to 1 iron cube.
2. If the base area of the container is 150 cm², find the difference in the volume between the iron cube and the plastic cube.  Express your answer in cm³.

(a)
2 plastic cubes → water level rises by 38 cm

Height of water per plastic cube
= 38 ÷ 2
= 19 cm

Height of water after one plastic cube is removed
= 89 + 38 - 19
= 108 cm

Height of water increased with 1 iron cube
= 132 - 108
= 24 cm

Ratio of the change in height of the plastic cube to the iron cube
= 19 : 24 

(b)

Difference between the height of the iron cube and the plastic cube
= 24 - 19
= 5 cm

Difference between volume of the iron cube and the plastic cube
= 5 x 150
= 750 cm³ 

Answer(s): (a) 19 : 24; (b) 750 cm³