Definition of arithmetic mean – UGC NET Question

The arithmetic mean is defined as the sum of all observations divided by the number of observations. It provides a central value that represents the data set as a whole. In data interpretation and aptitude questions, the arithmetic mean is often used to compare performance or compute expected values. Thus, the description in the question is precisely the standard definition of arithmetic mean.

Option A:
Median is the middle value when the data are arranged in ascending or descending order, not the sum divided by the number of observations. It is another measure of central tendency, but it is defined differently from the formula given in the stem. Therefore, median does not correspond to the description.

Option B:
Mode is the value that occurs most frequently in a data set. It does not involve summing all values or dividing by the count. As such, it does not match the phrase "sum of all observations divided by n" given in the question. Hence, mode is not correct here.

Option C:
Arithmetic mean is correct because it uses the exact procedure mentioned: adding all observations and dividing by their number. For example, the mean of 2, 4 and 6 is (2+4+6)/3 = 4. This measure plays a key role in many quantitative questions, making it essential for UGC NET aspirants to understand.

Option D:
Range is the difference between the maximum and minimum values in a data set. It measures dispersion, not central tendency, and does not involve any division by the number of observations. Therefore, range is unrelated to the description and cannot be the correct answer.