What action should be taken if one of the three closest measurements differs by more than 1 inch?

Taking an additional measurement and computing an average is the correct action when one of the three closest measurements differs by more than 1 inch. This method ensures accuracy and reliability in data collection, which is critical in procedures where precision is vital, such as in military operations or maintenance tasks.

This approach is based on the principle of verification, where discrepancies in measurements could indicate errors or issues in technique, equipment, or conditions. By taking an additional measurement, you can better determine the true value by mitigating the influence of any outlying measurement that could distort the results. Averaging allows for a balanced representation of the data, leading to more reliable conclusions.

In contexts where exact measurements are paramount, relying solely on the largest or smallest measurement could lead to erroneous decisions or actions based on flawed data. Ignoring the differing measurement entirely would not address the potential inconsistencies that could occur, which can have serious implications in operational settings. Therefore, the process of taking additional measurements and averaging them is both a practical and trustworthy method for ensuring accuracy.