The solid caused the water level for Trial 1 to rise from 25.2 to 30.7 mL. Since the solid did not react with or dissolve in the water, the volume of the solid in mL is represented by just the change in water levels. The volume of the solid is then given by

Volume of solid sample = (30.7 mL - 25.2 mL) = 5.5 mL
(which is only two significant figures)