Precision is defined as:

• A. How consistent a device is across repeated measurements
• B. How close measurements are to the true value
• C. The sample's density
• D. The energy range of the XRF

Answer: (A)

Precision is about how consistently the instrument gives the same result when you repeat measurements of the same sample under the same conditions. In XRF analysis, high precision means your readings cluster tightly around a single value from multiple scans, showing the instrument and method are repeatable and stable. This relies on good counting statistics, stable instrument performance, and consistent sample presentation.

Accuracy, by contrast, concerns how close those measurements are to the true or known value. The sample’s density and the energy range the instrument can detect don’t define precision; they affect other aspects of measurement, but not how repeatable the readings are. So the best choice describes repeatability, not closeness to the true value or other unrelated properties.