Which expression defines sample count in this context?

• A. (Sample count - Blank count) / Field area
• B. Sample count minus Blank count
• C. Field area times Sample count
• D. Flow rate divided by time

Answer: (A)

In this context, you want to express how many valid samples you have per unit area, so you can compare across different sites or field sizes. Subtracting the blank count from the sample count removes the contamination or control data that shouldn’t be counted as actual samples, giving you the net number of valid samples. Dividing that by the field area converts the total into a density—samples per unit area—so the measure is scalable and comparable regardless of how large or small the field was.

The other options don’t fit because subtracting blanks gives a net count but ignores area normalization, which is needed for meaningful comparison. Multiplying field area by sample count isn’t a sensible metric for sample density, and flow rate divided by time describes a volumetric rate, not a count of samples.