When I look at the odds for a football match they are presented as (for example):
Liverpool: 5/6
Draw: 5/2
Spurs: 10/3
How could I work out the % chances of a win based on the odds??
ie Liverpool 70%
Draw 20%
Spurs 10%
Wikipedia has a good discussion of this issue: Odds - Wikipedia, the free encyclopedia
I think the most common way odds are quoted is "odds against". You haven't specified whether, e.g., Liverpool 5/6 means odds for or odds against, so I'm going to assume the latter. But if you want to be sure, you have to find out from the bookie/betting site.
Also, odds don't translate directly into chances of winning. They reflect what most bettors think of a match plus the way bookies set their odds so that they win a bit more than they lose. But close enough.
So, assuming n/m odds against, your chances of winning are 1-n/(n+m). So 5/6 means your chances of winning are 1-5/11 = 54.5%. If you are quoted odds against of 9/1, your chances of winning are 1-9/10 = 10%.
How did you get 54.5% for Liverpool??
When I use that formula I get:
1-5/11 = -4/11 = -0.36 or 36%
The way I've been playing around with is to first reverse the odds, since the more chance of an outcome, then lower the payout, then get them on equat "footing":
Liverpool: 6/5 -> 12/10
Draw: 2/5 -> 4/10
Spurs: 3/10
Total: 19/10
Of course the total is greater than one, but that's the reverse payout. Now, you take each occurence on the total. (Results rounded to the unit.)
Liverpool: 12/19 -> 63%
Draw: 4/19 -> 21%
Spurs: 3/19 -> 16%
I'd rather find a formula that worked because I'd ultimatly like to use this in a database or excel spreadsheet