Does anyone want a mid-term exam so soon?

Analysis: The bottom area of the cuboid container is 3 * 1.5 decimeter, which means that the steel balls are completely immersed in the water, so the volume of the water surface rising is the volume of three steel balls. 4.5*0.6=2.7 cubic decimeter. The volume of three steel balls is 2.7 cubic decimeter, so the volume of one steel ball is 2.7/3=0.9 cubic decimeter.

Good luck in the exam.