After reading the guide already on the site, I felt like contributing some more to the laws of averages. While the statistics mentioned before are all very well and good, al they work out is your chance of getting a certain amount of wins via the possibilities – this takes into account the fact that if you lose once, that’s it. This basically works out the chance of getting to a certain round, depending on how many times you play, instead of just your chance of winning.

For those of a nervous disposition, look away now.

nCr x p^r x q^n-r = Probability of when you’ll lose depending on how many rounds you want to go for

where n=Highest round to play to (i.e. if you only want to go as far as round 5, n=5),
r=Round you reach,
p=Probability of winning round (in each case, 1/2) and
q=Probability of losing round (1/2 again).

Basically, it boils down to this.

If you’re going to stop at the 5th round, no more, no less, here’s how it is:

0.0313 chance of losing AT round 1
0.1562 chance of losing AT round 2
0.3125 chance of losing AT round 3
0.3125 chance of losing AT round 4
0.1562 chance of losing AT round 5
0.0313 chance of winning all 5 rounds

However, this is not the whole story….

0.0313 chance of losing BY round 1
0.1875 chance of losing BY round 2
0.5000 chance of losing BY round 3
0.8125 chance of losing BY round 4
0.9688 chance of losing BY round 5 – i.e. by the time you get this far,
0.9688 (97%) is the probability you’ve lost already.

Of course, this is only if you intend to go as far as the 5th round, but bearing in mind you actually only have a probability of 0.0156 ((1/2)^5) of getting that many wins (i.e. five out of five), it doesn’t seem likely you’ll get much further.

Simply put, if someone tells you they won millions on Double Or Nothing, they cheated or they’re lying! – tsrx3am