Final answer:
Bryan is correct because there are several methods to calculate volume. If the cork's shape is simple enough, geometric formulas can be utilized instead of the water displacement method.
Step-by-step explanation:
Bryan is correct that it is not necessary to use a pebble to find the volume of the cork. There are different methods to calculate the volume of an object, and using a pebble is indicative of a particular method called water displacement. To use this method, one would submerge the cork in water and measure how much the water level rises, which is equal to the volume of the cork.
However, if the shape of the cork allows, one could simply use geometric formulas to calculate the volume directly. For example, if the cork is cylindrical, the volume can be found using the formula V = πr^2h, where V is the volume, r is the radius of the base, and h is the height of the cylinder.