It depends on what the second method is!
Archimedes
It depends on what the second method is!
The Proper way to find the density of an object is by dividing the objects Mass by its Volume. (Density broke my Heart) Mass/Volume = Density
There are 12 inches.
A graduated cylinder may be used for small objects that are insoluble in a selected liquid. But that method would not work for determining the volume of a sugar cube (soluble in water) or a motor car (won't fit in a graduated cylinder!).
breakeven analysis
The method for determining the volume of a solid depends on its shape. The volume of a solid object with a regular geometric shape (rectangular box, cube, cylinder, sphere) can be determined using the volume formula for the shape. Because many objects are not regularly shaped their volume cannot be determined using a volume formula. The volume of these objects can be found by water displacement. A volume of water sufficient to cover the object is placed in a graduated cylinder and the volume read. The object is added to the cylinder and the volume read again. The difference between the two volumes is the volume of the object.
The method you would use is to take a graduated cylinder, face the markings towards you, fill the cylinder with a liquid that won't react with said object (usually water is fine) to an appropriate measure (around half way depending on the size of the object), record the volume before placing the object in the fluid, place the object in the fluid and record the volume after, subtract the initial from the total (liquid +object's displacement) and you will have the objects volume. However you must be aware that certain objects will float or at least have some amount of buoyancy making determining it's volume harder to ascertain (if at all possible) with this method.
breakeven analysis
This is a poor question. There is no way such a method can measure the volume of a sugar cube, for example, because it will dissolve in the water.
breakeven analysis
The volume of the metal cylinder is 21.4mL - 15mL = 6.4mL. This is the water displacement method for determining the volume of an irregular solid.