Isn’t this rather similar to another recent thread of yours on the very same topic, that seems to have been well covered in quite high detail?
Display element when specific option is selected
The code from your own post #3 shows the following jQuery code:
$("#location").change(function(){
if($(this).val()=="loc5")
{
$("div#container").show();
}
else
{
$("div#container").hide();
}
});