basic probability question counter intuitive?

[arden street]

well it's counter intuitive for me at least [img]/images/graemlins/confused.gif[/img] and not so basic! [img]/images/graemlins/tongue.gif[/img]

so i'm trying to figure out the % chance of hitting an Ace or a King on the flop when you hold AK and are heads up and you're assuming your opponent doesn't hold an A or a K.

there are 3 remaining Aces and 3 remaining Kings available and i thought the equation was 6/48 + 6/47 + 6/46 = .383?

but that's wrong apparently?

could someone please give me the correct formula?

and if anyone wanted to explain why the 'intuitive' formula is wrong that would be appreciated too!

cheers