Another probability question


Well-known member
May 19, 2009
I can’t help feeling that even with a fairly weighted coin, you’d have a 90% probability of getting more heads than tails a lot sooner than 41.
Depends on the weight of the coin. 60% isn't much far from 50% standard coin, so it makes sense you'd have to toss it many times to reach that confidence level.

Perhaps my grasp of probability is so far out of whack with reality (wouldn’t be the only thing that is)
Definitely true in your case !
Likes: TheBramble


Active member
Jan 17, 2005
I would never have 90% confidence. The only way you can be any more "confident" is to record what was thrown before.

If i threw a tails, the chance was 0.4 = 40%
I Threw again, the chance of another tails is 0.4 x 0.4 = 16% Threfore chance of heads = 84%
I Threw again, the chance of yet another tails is 0.4 x 0.4 x 0.4 = 6.4% therefore Heads = 95.4%

You could say "statistically" the chances of a heads are improving but they are still really only 60% each time as each toss is independant of the previous tosses :smart:

I think thats right. Would've been easier to look at google instead of giving me the opportunity to waste my time! :idea: