so to start, you come up with equations for full volume and for the current volume. the volume of a cylinder is V=3.14r^2h and to find the height to start we plug in the radius (5) and the volume (471). 471=3.14(25)h and solve for h. h=6 when it is full. Then, we do the same thing to the second one where the volume is 314 and the radius is obviously still 5. 314=3.14(25)h and the height comes out to be 4. 6-4=2 so the difference between the two is 2.