Using simultaneous testing for real estate transactions, if the readings are 3.8 and 5.2 pCi/L, what is the relative percent difference?

To calculate the relative percent difference between the two radon readings of 3.8 and 5.2 pCi/L, you first need to determine the absolute difference between the two values. This is done by subtracting the smaller reading from the larger one:

5.2 - 3.8 = 1.4 pCi/L.

Next, to get the relative percent difference, you take this absolute difference and divide it by the average of the two readings. The average is calculated as follows:

(3.8 + 5.2) / 2 = 9.0 / 2 = 4.5 pCi/L.

Now, divide the absolute difference by the average:

1.4 / 4.5 ≈ 0.3111.

Finally, to convert this decimal into a percentage, multiply by 100:

0.3111 * 100 ≈ 31.11%.

When rounded, this value is 31%, which corresponds to the answer choice provided. Therefore, 31% is the relative percent difference between the two readings, making it the correct answer. This calculation is crucial in radon testing as it helps assess the consistency of readings, particularly in real estate transactions where accurate measurements