Something

/*MEAN*/
$mean_q = mysql_query("SELECT tmpSeconds FROM data WHERE name = '". mysql_escape_string($name) ."'");

$seconds= array();

while ($row= mysql_fetch_assoc($mean_q)) {
        array_push($seconds, $row['tmpSeconds']);
}       

$sum= array_sum($seconds);
$average = date("i:s", round($sum / count($seconds)));