The <em>mean</em> of a <em>set</em> of numbers is the <em>sum</em> divided by the number of <em>terms</em>.
Arrange the <em>data</em> in an ascending order and the <em>median</em> is the middle value. If the number of values is an <em>even number</em>, the <em>median</em> will be the <em>average</em> of the two middle numbers.
The <em>mode</em> is the <em>element</em> that occurs most in the <em>data set</em>. In this case, 18 occurs 4 times.
