So I'm considering doing some binary trades on BtcOracle, here are the odds when guessing if the price will go higher:

http://i.imgur.com/UXtdG1p.png

So I'm wondering if it's possible to calculate from these odds what their fee is? I would also like to know how often I need to be right if the return is say 1.25 (if you're wrong you lose your btc).