title: Calculate bottom 10% and top 10% values from quartile values
body: <p><strong>UPDATE</strong>: I found the following <a href="http://mathnetnumerics.codeplex.com/wikipage?title=Statistics&amp;referringTitle=Documentation" rel="nofollow">C# Library</a>, and it is perfect for what I need.</p>
  
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  <p>So I have a collection of data points, for example: 4, 5, 2, 3, 15, 3, 3, 5
  I have then calculated out the upper (Q2) and lower quartiles (Q1), which are 5 and 3 respectively.</p>
  
  <p>Because of the quartiles I can reference from the lowest number to the Q1 to target the low 25% and then from the hightest value to Q2 to target the top 25%. Because I now have Q1 and Q2 I can also target the inner 50% of the values.</p>
  
  <p>With this information I want to be able to figure our where 90% of the data falls and I haven't been able to find anywhere online that references getting any other percentages other than 25%.</p>
  
  <p>If it helps, my server side language that I am doing these computations on is C# with .NET 4.5, but I am wanting to know the math behind it more than the programmatic way to accomplish it.</p>
  
  <p>Any help is greatly appreciated. Hopefully what I have written is clear enough.</p>
  
  <p>Thanks.</p>