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The mean of a set of numbers, sometimes simply called the average , is the sum of the data divided by the total number of data.
Example 1 :
Find the mean of the set .
There are numbers in the set. Add them all, and then divide by .
So, the mean is .
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 are numbers in the set, and they are arranged in ascending order. The middle number (the th 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 are numbers in the set -- an even number. So, find the average of the middle two numbers, and .
So, the median is .
The mode of a set of numbers is the number which occurs most often.
Example 1 :
Find the mode of the set .
, , , and each occur once.
occurs twice and occurs three times.
So, is the mode.
Example 2 :
Find the mode of the set .
In this case, there are two modes -- and both occur twice, whereas the other numbers only occur once.