In calculating substrate correction, which of the following is the formula used?

The formula for calculating substrate correction involves averaging the readings to find a representative value that accounts for variations in the data. The average of all readings effectively normalizes the data, providing a central tendency that helps in adjusting for any background noise or inconsistencies. This method ensures that the substrate correction reflects the typical values encountered in the assessment, making it a more reliable metric for evaluating lead levels.

Using the other methods, such as the sum of readings divided by the number of samples or a weighted average, while relevant in other contexts, does not specifically cater to the needs of lead risk assessment regarding substrate correction. The median, which represents the middle value in a dataset, is also not suitable in this scenario since it does not consider the overall distribution of values as effectively as the average does. Hence, the average of all readings is the ideal approach in this context.