Mean Proportional
In a proportion with three terms, the mean term is the mean proportional between the two other terms.
The expression "mean proportional" is a synonym of "geometric mean".
Example
Consider this proportion:[latex]\dfrac{2}{x}[/latex] = [latex]\dfrac{x}{8}[/latex]
The term [latex]x[/latex] is a mean proportional. We can calculate it with the geometric mean :[latex]\overline{x}_g[/latex] = [latex]\sqrt[2]{2 × 8}[/latex] = [latex]\sqrt[2]{16} = 4[/latex]