The original math question was answered correctly, by MudGuard, in the first reply.

Additional information, which wasn't requested but which is needed to "meet the need," has been supplied by a couple of citations where the actual tax tables can be found. (Politicians don't always do "real" math, so you've got to get their forms.)

As to Mrzzy's little asses. In the first case, you have three doors which we assume are equally likely to have your preferred "prize." Odds are one in three, regardless of which door you choose - so it really doesn't matter which one you pick.

When the other door is opened to reveal an ass, you have a new problem. You now have two remaining doors, each of which is presumed to have equal likelyhood of having your "prize." Odds are NOW 1 out of 2 that you will pick the right one - so it makes NO DIFFERENCE whether you keep the same door or pick the other one.

The only ODDS that matter are the ones that apply when you put your money down. That's why the good poker player pays as much attention to what his opponents show as to his own hand.

The clinker in Mrzzys little asses is that this situation only appears on quiz shows, where the guy behind the scenes will put what they WANT you to get behind whichever door you pick - which depends entirely on whether they've decided they need a winner or a loser to boost ratings.

John