Need help with Vegas odds

If you google "determining odds in vegas", a bunch of pages come up with how they determine them for sports.

I don't *think* the odds would come up to 100%, and here's why: each odd is detemined by the chances of *that* contestant to win. So, with three players, two of them could have a 50/50 chance (meaning they're both very good and it's anyone's guess), with the third player having, say, a 30% chance, because he's not as good but there's something about him that makes people think maybe he could come from behind and take it. So that's 130%.

Besides looking at the sports betting, have a look at horse racing.

When in Vegas, I play slots. Big bets make me queasy.

The easiest way to do something like this would be paramutual wagering, (Sidow was right on with the horse racing) In that kind of betting the odds are determined by the money bet as opposed to establising what Vegas calls "a line". If equal amounts are bet on each of your contestants then the odds will reflect that. A simple ex: 3 contestants, each has 90 dollars place upon them to win, total win pool equals $270. the odds are 2-1 on each player because 2 of the players will lose and the money bet is equal. Now, say that $90 is bet on one player and $45 is bet on the other two each. The win pool is $180 but the odds are twice as good for the $90 player than the $45 the $90 players odds = 1-2 but the $45 players are now 3-1. Again this is very simple. but its really a matter of money bet, amount of people wagering, and amount of contestants.
Now of course this dosen't count the vig (vigourous) paid to the betting establishment and included in all bets or taxes and stuff.

If it were just 3 candidates and they were relatively close, the odds might look like this:

Joe Favorite 3-1
Bob Frontrunner 12-1
Bill Longshot 20-1