Final answer:
When the air content exceeds the 9% range of the meter, one should report the excess content rather than attempting to dilute the sample or use a different meter.
Step-by-step explanation:
If the air content is greater than the 9% range of the meter, the correct course of action is to (c) Report the excess content. This is because the meter is designed to measure a specific range, and values outside this range cannot be accurately determined by dilution or using a different meter.
When dealing with analytical procedures such as adding greater amounts of chlorine to samples from the water supply to determine the chlorine residual, it's crucial to adhere to the specific protocols. If the changes in concentration are greater than 5%, this exceeds the maximum value for disregarding the change, indicating that the sample either exceeds the measuring capacity of the equipment or is not within the intended range for accurate measurement, therefore reporting is the appropriate step.