What is the Relative Percent Difference (RPD) if one test result is 8.7 pCi/L and another is 7.3 pCi/L?

To calculate the Relative Percent Difference (RPD), you use the following formula:

[ RPD = \frac{|Value_1 - Value_2|}{\frac{(Value_1 + Value_2)}{2}} \times 100 ]

In this case, the two test results are 8.7 pCi/L and 7.3 pCi/L.

1. First, calculate the absolute difference between the two values:

[ |8.7 - 7.3| = 1.4 ]

2. Next, calculate the average of the two values:

[ \frac{(8.7 + 7.3)}{2} = \frac{16.0}{2} = 8.0 ]

3. Now, plug these values into the RPD formula:

[ RPD = \frac{1.4}{8.0} \times 100 = 17.5% ]

The calculation leads to a Relative Percent Difference of 17.5%. This percentage provides a measure of the variability or consistency between the two radon test results. The RPD is a critical metric in radon testing as it helps assess