a Cointoss not 50/50

[HavanaBanana]

Scientists have been studying the cointoss and have come to the conclusion that it is not 50/50.
I must have known this instinctively as I have always thrown the coin with the right side up /images/graemlins/smile.gif

Here is the link: Cointoss, not a Cointoss (http://www.sciencenews.org/articles/20040228/fob2.asp)

[irchans]

[BruceZ]

This could be fixed to any desired accuracy very quickly by flipping the 51% coin multiple times, turning it over after each flip so it starts with the side up that it landed on last time. Note that if you just flipped it twice, the probability of getting the same side you start with becomes .51*.49 + .49*.51 = .4998, almost fair already!

[toots]

Several years ago, I read a short article on training one's self to flip coins predictably (standard thumb and fist flip). Apparently, some people have good enough muscle control to be able to significantly slant the odds on their flips.

Which leads me to the following revision to a standard probability problem:

Q: Someone's tossed a coin, and it's come up heads 10 times in a row. What's the probability of it coming up heads on the 11th flip?

Wrong Answer: "One in a couple thousand, because I'm a gambler, and I never quite figured out this probability stuff."

Possible right answer: 50/50, because I learned my statistics from a book

Possible right answer: 100%, because he's probably using a two-headed coin (it's rigged)

Possible right answer: 80%, because the guy obviously knows how to rig the toss.

And, oh yeah, don't forget the psychologist's answer: "The coin has no tails, p<.001."

[Sloats]

How could everyone neglect the probability that the coin will land on its side?

[daryn]

or that the coin won't even come down? remember the chances of the laws of physics completely and spontaneously breaking down are 100^100-1 against

[SossMan]

This slight bias pales when compared with that of spinning a coin on its edge. A spinning penny will land as tails about 80%

Okay, I'm offering $2 for every time it lands on heads and taking a buck every time it lands on tails. Gonna give my home game an "earfull of cider". LOL!

[bigpooch]