On the final split, how should the masses of the two halves compare?

When evaluating the masses of the two halves in a final split, the expectation is that they should closely match each other to ensure consistency and accuracy in aggregate sampling. A tolerance of within +/- 10% is generally recognized as acceptable for these types of measurements. This range allows for minor variations that can occur due to factors like sample handling, moisture content, and inherent variability in the material.

By maintaining a tolerance of +/- 10%, it ensures that the results remain reliable for the purpose of quality control and analysis without being overly stringent. If the masses were required to be exactly equal or within tighter margins, it could lead to impracticalities in real-world scenarios where small discrepancies are unavoidable. Therefore, the answer that specifies within +/- 10% appropriately reflects the expected reliability while acknowledging the natural variability in material sampling.