Which reading would be classified as negative with respect to the 1.0 mg/cm2 standard?

Which reading would be classified as negative with respect to the 1.0 mg/cm2 standard?

• A. 1.2 mg/cm2
• B. 0.5 mg/cm2
• C. 1.0 mg/cm2
• D. 2.0 mg/cm2

Answer: (B)

The essential idea is comparing the measurement to the 1.0 mg/cm2 limit: readings below the limit are negative, while readings at or above the limit are positive. A reading of 0.5 mg/cm2 is below 1.0 mg/cm2, so it is negative with respect to the standard. Readings of 1.2 mg/cm2 and 2.0 mg/cm2 are at or above the limit and would be considered positive, while 1.0 mg/cm2 is at the threshold and treated as positive in this context.

The essential idea is comparing the measurement to the 1.0 mg/cm2 limit: readings below the limit are negative, while readings at or above the limit are positive. A reading of 0.5 mg/cm2 is below 1.0 mg/cm2, so it is negative with respect to the standard. Readings of 1.2 mg/cm2 and 2.0 mg/cm2 are at or above the limit and would be considered positive, while 1.0 mg/cm2 is at the threshold and treated as positive in this context.