Difference between revisions of "Median (statistics)"

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== Definition ==
 
== Definition ==
The '''median''' of a set of numbers is the middle element in a set when the elements are written in order (i.e. least to greatest).  When the number of elements is even, there are two middle elements and so the average of the two is taken to be the median. These show up frequently on contest problems, and also in [[statistics]]. For example, to find the median of the set {5, 3, 9, 7}, we would first write it in order {3, 5, 7, 9}. Then, to find the median, we take <math>\displaystyle\frac{5+7}{2}=6</math>  
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The '''median''' of a [[finite]] [[set]] of [[real number]]s is the middle [[element]] of the set when the elements are written in order (i.e. least to greatest).  When the number of elements is even, there are two middle elements and so the [[arithmetic mean]] of the two is taken to be the median.  
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For example, the median of the set <math>\{2, 3, 5, 7, 11, 13, 17\}</math> is 7.  In order to find the median of the set {5, 3, 9, 7}, we would first write it in order {3, 5, 7, 9}. Then, to find the median, we take <math>\displaystyle\frac{5+7}{2}=6</math>.
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The median is one of several different [[mean]]s for a set of numbers.  It appears most frequently in the field of [[statistics]] and also occasionally on mathematical contests. 
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== Problems ==
 
== Problems ==
 
Find the median of {3, 4, 5, 15, 9}.
 
Find the median of {3, 4, 5, 15, 9}.
  
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{{problems}}

Revision as of 10:43, 24 July 2006

Definition

The median of a finite set of real numbers is the middle element of the set when the elements are written in order (i.e. least to greatest). When the number of elements is even, there are two middle elements and so the arithmetic mean of the two is taken to be the median.

For example, the median of the set $\{2, 3, 5, 7, 11, 13, 17\}$ is 7. In order to find the median of the set {5, 3, 9, 7}, we would first write it in order {3, 5, 7, 9}. Then, to find the median, we take $\displaystyle\frac{5+7}{2}=6$.

The median is one of several different means for a set of numbers. It appears most frequently in the field of statistics and also occasionally on mathematical contests.

Problems

Find the median of {3, 4, 5, 15, 9}.

This page is in need of some relevant examples or practice problems. Help us out by adding some. Thanks.