Range in a measured quantity can be defined as which of the following?

• A. The difference between the highest and lowest operational values.
• B. The region between lower and upper limits within which a quantity is measured.
• C. The average value of the measurements over time.
• D. The standard deviation of the measurements.

Answer: (A)

The range measures how much a set of measurements varies, and it is defined as the difference between the highest and the lowest observed values. This directly captures the overall spread of the data: you look at the extreme ends of your measurements and subtract to see how far apart they are. For example, if readings go from 3 to 9, the range is 6, showing the full extent of variation.

The other descriptions describe different concepts. The region between lower and upper limits refers to an acceptable window or the instrument’s measurement range, not the actual spread of observed values. The average value represents the central tendency, not how spread out the data are. The standard deviation measures dispersion around the mean and can be related to spread, but it depends on all values and doesn’t equal the simple outer range.