The mean of a set of data can be easily approximated by taking an average of the values in that data. In order for the mean to be representative, the group of numbers must be comparable values in the same category.
Analyze the data
Look at the values in the data table. Examine a single category's records. For example, if you are looking at a table of times at which races were completed, look at only the times logged for one event or possibly one athlete.
For many sets of data, there are some values that are too high or too low to be included when finding the mean, especially if there are many values in the data table. For example, if you are looking for the mean race time for a group of high school athletes, you might eliminate the times that are much longer than the bulk of the others. These values are easier to pick out if you know the circumstance or reason for the outline, such as an injury that occurred during the race.
Take the average
Add together the values you are using. Divide the sum by the total number of values you examined. For example, if values in one category of a data table are 8, 11, 13, 12, 8, 10, 9 and 10, the average is 10.125 (81/8=10.125).