title: html standard deviation code
body: <p>I am trying to code this formula (standard deviation):</p>
  
  <pre><code>       ____________  
     δ =√∑(xi - µ)2
              n
  </code></pre>
  
  <p>My html code is:</p>
  
  <pre><code>&lt;table border="0" cellspacing="0" cellpadding="0" width="180"&gt;
      &lt;tr&gt;
          &lt;th width="180" colspan="3"&gt;&lt;p align="center"&gt;&lt;strong&gt;Population Standard Deviation&lt;/strong&gt;&lt;/p&gt;&lt;/th&gt;
      &lt;/tr&gt;
      &lt;tr&gt;
         &lt;td width="40" valign="top"&gt;&lt;p align="center"&gt;&amp;nbsp;&lt;/p&gt;&lt;/td&gt;
         &lt;td width="50" rowspan="4"&gt;&lt;p align="right"&gt;&amp;radic;&lt;/p&gt;&lt;/td&gt;
         &lt;td width="90" valign="bottom"&gt;&lt;p align="left"&gt;__________&lt;/p&gt;&lt;/td&gt;
      &lt;/tr&gt;
      &lt;tr&gt;
          &lt;td width="60" rowspan="2"&gt;&lt;p align="centre"&gt;&lt;strong&gt; &amp;#948; =&lt;/strong&gt;&lt;/p&gt;&lt;/td&gt;
          &lt;td  width="90"&gt;&lt;p align="center"&gt;&lt;strong&gt;∑(x&lt;sub&gt;i&lt;/sub&gt; -µ)&lt;sup&gt;2&lt;/sup&gt;&lt;/strong&gt;&lt;/p&gt;&lt;/td&gt;
      &lt;/tr&gt;
      &lt;tr&gt;
          &lt;td width="90"&gt;&lt;p align="center"&gt;n&lt;/p&gt;&lt;/td&gt;
      &lt;/tr&gt;
  </code></pre>
  
  <p></p>
  
  <p>The challenge I have is to get the formula to be well positioned. I was thinking the row height would help but from further reading the row and column span would nullify it. So how can I best present this formula? 
  I also have a challenge in adding the division line right below the summation (row3). I tried using CSS but it would mean having the subscripts and superscripts underlined. Is there a better code for this as well? Thanks.</p>