Mean, Median, and Mode
The Mean of a Data Set
The mean of a set of numbers, sometimes simply calledthe average, is the sum of the data divided by the total number of data.
Example 1:
Find the mean of the set.
There arenumbers in the set. Add them all, and then divide by.
So, the mean is.
The Median of a Data Set
The median of a set of numbers is the middle number in the set (after the numbers have been arranged from least to greatest) -- or, if there are an even number of data, the median is the average of the middle two numbers.
Example 1:
Find the median of the set.
There arenumbers in the set, and they are arranged in ascending order. The middle number (theth one in the list) is. So, the median is.
Example 2:
Find the median of the set.
First, arrange the numbers in ascending order.
There arenumbers in the set -- an even number. So, find the average of the middle two numbers,and.
So, the median is.
The Mode of a Data Set
The mode of a set of numbers is the number which occurs most often.
Example 1:
Find the mode of the set.
,,,andeach occur once.
occurs twice andoccurs three times.
So,is the mode.
Example 2:
Find the mode of the set.
In this case, there are two modes --andboth occur twice, whereas the other numbers only occur once.