Watu output error

I loaded up your plugin looking to make some tests for a friend that was looking into using you plugin for it. Everything went really smooth, I really loved the easy of usage. I ran into an error after I tested my first tests an saw I was getting a “divide by zero” errer just above the results. is this common or have I messed the settings?

Error

Warning: Division by zero in /home/defken/defango.com/wp-content/plugins/watu/show_exam.php on line 76

link to test

http://defango.com/low-t/

lines from show_exam.php

$result .= “”;
if(!$_REQUEST[“answer-” . $ques->ID]) $result .= “<p class=’unanswered’>” . __(‘Question was not answered’, ‘watu’) . “</p>”;

$result .= “</div>”;
//$total++;
}
$total = $wpdb->get_var($wpdb->prepare(“SELECT sum(point) FROM {$wpdb->prefix}watu_question as q inner join {$wpdb->prefix}watu_answer as a on question_id=q.ID WHERE exam_id=%d and correct=’1′ “, $exam_id));

//Find scoring details of this guy.
$percent = number_format($score / $total * 100, 2);
//0-9 10-19%, 20-29%, 30-39% 40-49%
$all_rating = array(__(‘Failed’, ‘watu’), __(‘Failed’, ‘watu’), __(‘Failed’, ‘watu’), __(‘Failed’, ‘watu’), __(‘Just Passed’, ‘watu’),
//

any help would be great!

http://wordpress.org/extend/plugins/watu/