The average of a set of data is the sum of all the data in that set divided by the number of data points



For example, in the data set below

4,9,2,5,10

(4+9+2+5+10)/5 = 6

Compare the average value to the median of a set of data. The median of the above data would be 5. In general, unlike the median the average of a set of data can be distorted easily by a few very large values: the average net worth of 5 Tech chemistry professors + Bill Gates would be on the order of 15 billion/person. Needless to say, the writer of this document does not have $15 billion. The median would be much closer to the actual net worth of Tech professors.

Example: What is the average of the following set of data? What is the median?

1.546,2.443,1.896, 1.499, 1.562, 1.689, 1.480

To get the average, sum all the numbers and divide by the number of data points (7)

average = (1.480+1.499+1.546+1.562+1.689+1.896+2.443)/7

average = 1.731

The median is just the middle value. If we put all the data in order

1.480, 1.499, 1.546, 1.562, 1.689, 1.896, 2.443

Information provided by: http://learn.chem.vt.edu