ANSWER: 26.81 mL
Convert mg of silver to grams of silver using unit conversion
4287mg silver * (1g/1000mg)=4.287g silver
Convert grams of silver to mL of silver using density
4.287g silver / 10.5g/mL = 0.408 mL silver
Add mL of silver to mL of water and that is the final water level in the cylinder
26.4 mL water + 0.408 mL silver = 26.808 mL