Difference between revisions of "Median (statistics)"

(problem formats, LaTeX)
(No difference)

Revision as of 21:23, 24 November 2007

A median is a common type of mean for a set of numbers.

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 $\frac{5+7}{2}=6$.

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

Pre-introductory

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

Introductory

Intermediate

Olympiad

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