Mean
The mean of a group of numbers (data) is the average of the group of numbers.
Example: Find the mean of the following data:
75, 68, 97, 76, 100, 68, 92, 69, 100, 97, 56
The sum of the numbers is 898. There are 11 numbers in the list. Thus, the average/mean of the data is 898/11 = 81.64 (Rounded to the nearest hundredth).
Median
The median of a group of numbers is found by listing the numbers from least to greatest. The number located in the middle of the list is the median of the group. (If the group contains an even number of numbers, then the median of the group is the average of the two middle numbers.)
Example: Find the median of the following data:
75, 68, 97, 76, 100, 68, 92, 69, 100, 97, 56
The data listed from least to greatest is as follows:
56, 68, 68, 69, 75, 76, 92, 97, 97, 100, 100
The middle number in the list of data is 76. Thus, 76 is the median of the data.
Mode
The mode of a group of numbers is the number that occurs most frequently in the list or group. It is possible for there to be more than one mode in a group of data.
Example 1: Find the mode of the following data:
75, 68, 97, 76, 100, 68, 92, 69, 100, 97, 56
The numbers 100, 97, and 68 all occur twice in the data, which is more than any of the occurance of any of the other data in the list. Thus, the modes for this list of data are 100, 97, and 68.
Example 2: Find the mode of the following data:
2, 3, 4, 9, 3, 7, 5, 6, 2, 4, 8, 2, 7, 8, 2, 3
Several numbers occur more than once in the data. However, the number 2 occurs more than any other number (4 times). Thus, 2 is the mode for this set of data.