Solution: the volume of water is: 16*6=96 cubic decimeter;

After adding iron blocks, the water surface will rise. At this time, the whole volume should be the volume of raw water plus the volume of iron, that is, 96+24= 120 cubic decimeter;

Now the volume has been calculated. Divided by the bottom area of the container, it is the height of the water surface: 120/ 16=7.5 decimeter.