JQuery Selector

<script language="javascript" type="text/javascript">
$(document).ready(function(){
 $(".BookTable input[name=attended]").click(function() {

     if ($(this).attr("checked") == true)
   {
         $("input").parent().parent("input[name=attended]").attr("checked","yes");
   }
 });
});
</script>

<table class="BookTable adj-table">
<tr>
<td>Joe</td>
<td>Bloggs</td>
<td><input name="booking" id="booking"  type="checkbox" value="1" /></td>
<td><input name="attended" id="attended"  type="checkbox" value="1" /></td>
</tr>
<tr>
<td>Dave</td>
<td>Smith</td>
<td><input name="booking" id="booking"  type="checkbox" value="1" /></td>
<td><input name="attended" id="attended"  type="checkbox" value="1" /></td>
</tr>
</table>