title: jquery get value from a radio button group
body: <p>I have two simple groups of radio button, like this:</p>
  
  <pre><code>Yes&lt;input type="radio" name="first" value="yes"&gt; No&lt;input type="radio" name="first" value="no"&gt;&lt;br&gt;
  Yes&lt;input type="radio" name="second" value="yes"&gt; No&lt;input type="radio" name="second" value="no"&gt;
  &lt;h4 class="result"&gt;&lt;/h4&gt;
  </code></pre>
  
  <p>And I will set them into like this: </p>
  
  <ul>
  <li>If both of groups have "No" value, then the result in h4 is "Low"</li>
  <li>If both of groups have "Yes" value, then the result is "High"</li>
  <li>If both of groups have different value which is "yes" and "no" the result will be "Medium"</li>
  </ul>
  
  <p>And so, I want to make it into jQuery with change event, how can I do that? </p>