Final answer:
Sample A, which displaces twice as much water as sample B, has the larger volume, since the displaced water volume is directly proportional to the object's volume.
Step-by-step explanation:
If two samples, A and B, each of equal mass are placed separately in graduate cylinders containing 5.00 mL of water, and sample A displaces twice as much water as sample B, it indicates that sample A has a larger volume than sample B. This is because the volume of a submerged object is directly proportional to the volume of water it displaces. Given that the masses of the samples are equal, the one displacing more water (in this case, sample A) will have the larger volume.