Coin Flip Odds

jay helfert said:
I will only say this once. The odds on a coin flip are not exactly 50-50. It is more like 52.5-47.5 Tails. There is a reason for this that I won't go into here. Some of you may already be aware of this.

Try flipping a quarter 100 times on a pool table. Watch what happens. I'm betting Tails comes up a little more.

Thanks a lot Jay, you just blew my advantage on the flip!!
 
jay helfert said:
I will only say this once. The odds on a coin flip are not exactly 50-50. It is more like 52.5-47.5 Tails. There is a reason for this that I won't go into here. Some of you may already be aware of this.

Try flipping a quarter 100 times on a pool table. Watch what happens. I'm betting Tails comes up a little more.

I agree with what you're saying, but 100 times is way too small of a sample size, I wouldn't be surprised if it landed on heads 70% of the time over a 100 flip sample size.
I think the variance in flipping a coin probably takes at least a few thousand flips for the variance to even begin to even out.
I would assume a true figure wouldn't show up for around 50-100k attempts.

Sorry I just have to be a nit, lol.
 
"WHEN FLIPPING A COIN FOR SOMETHING, YES IT IS ALWAYS A 50/50 BET WITH A FAIR COIN, LET THE OTHER PERSON CALL HEADS OR TAILS AS STUDIES SHOW THAT PEOPLE CALL HEADS 80% OF THE TIME THUS PROVIDING YOU WITH A HUGE EDGE OVER THE LONG TERM."

You're kidding, right? Even if the other person calls heads 100% of the time you have no advantage (assuming each toss is 50/50).
 
Creole said:
I once lost nine coin tosses in a row for 50$ a toss. The crazy thing, I called heads everytime; I was sure it had to land on heads sooner or later, it never did!

The odds of nine tails in a row are no less and no more than any other series of nine outcomes. For example, the odds of THTHTHTHT are exactly the same as TTTTTTTTT.
 
Speaking of probabilities, here is an interesting one. Suppose you know that your neighbors have two children, and that at least one of them is a boy. Suppose further that for any given birth the odds are exactly 50/50 of a boy versus a girl.

Given what you know, what are the odds that both of your neighbor's children are boys?
 
Always Call Tails On A Coin Flip

After reading all of the post, I find it hard to believe that no one has come up with the only logically reason to call tails. If you notice, the head side of the coin is heavier than the tail side due to the extra silver it takes to make the head, therefore gravity comes into play during the flip and usually causes the coin to land head down. If you don't beleive me.....just ask FATBOY.:cool:
 
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Since there have been 6 pages of it is a 50/50 proposition-

What is the most that someone has ever seen bet on a coin flip? Eddie Broadway, a long time gambler in STL, came into the pool room late one night looking for a game. No one would play him in the games he wanted. So he takes out his bankroll, which is a few inches thick rubber banded together, and throws it on the table, saying "If no one will gamble at pool, flip a coin for that." Without hesitation, the vendor of the pool room just happened to be there and calls out "Tails". They flip the coin, in lands on tails and Eddie says - "Now that is gambling". The Vendor had no idea how much the bankroll was. He counted it afterwards, it was $5600+.
 
The 50/50 doesnt mean it has to end up 50 times heads and 50 times tails if you flip it 100 times. The 50/50 means you have 2 choices, heads or tails. So with 2 choices, it HAS to land on one or the other so you have a 50% chance it will land on heads and a 50% chance it will land on tails each flip.

Southpaw
 
jay helfert said:
I will only say this once. The odds on a coin flip are not exactly 50-50. It is more like 52.5-47.5 Tails. There is a reason for this that I won't go into here. Some of you may already be aware of this.

Try flipping a quarter 100 times on a pool table. Watch what happens. I'm betting Tails comes up a little more.

Jay, if what you say is correct, it is most likely that the Head side may be slightly heavier than the Tails side, altering the theoretical odds slightly. But without any bias, skill, or other outside influences, the theoretical odds for the outcome of two equal probabilities is 50/50, and prior tosses have zero effect on any current toss.

Jim
 
The odds is 50/50 but if you flip the coin AND call it, the odds become longer b/c we all have crappy luck. :P
 
PoolBum said:
Speaking of probabilities, here is an interesting one. Suppose you know that your neighbors have two children, and that at least one of them is a boy. Suppose further that for any given birth the odds are exactly 50/50 of a boy versus a girl.

Given what you know, what are the odds that both of your neighbor's children are boys?

Heads a boy, Tails a girl.:rolleyes:

Jim
 
PoolBum said:
Speaking of probabilities, here is an interesting one. Suppose you know that your neighbors have two children, and that at least one of them is a boy. Suppose further that for any given birth the odds are exactly 50/50 of a boy versus a girl.

Given what you know, what are the odds that both of your neighbor's children are boys?

I thinks its actually like 3-1.

Southpaw
 
Jigger said:
If I remember my statistics correctly:

The odds of 7 consequetive flips coming up heads (or tails) is actually 49.

( # of flips squared or in this example 7 X 7 )

Where did I see the website offering two headed coins etc....?

Assuming 50/50, the odds of seven consecutive heads is 1 in 128.
 
PoolBum said:
I'll take that bet.

No bet.;)

I misread you supposition, I thought the question was the probability of what sex a third child would be.

Jim
 
PoolBum said:
Speaking of probabilities, here is an interesting one. Suppose you know that your neighbors have two children, and that at least one of them is a boy. Suppose further that for any given birth the odds are exactly 50/50 of a boy versus a girl.

Given what you know, what are the odds that both of your neighbor's children are boys?

The odds that they are both boys are 2 to 1.
 
PoolBum said:
Assuming 50/50, the odds of seven consecutive heads is 1 in 128.

How did you arrive at that PoolBum? Might have fried that corner of my brain containing stat calculations...:p
 
PoolBum said:
The odds that they are both boys are 2 to 1.

Thats incorrect. The different possibilities are:

BB
BG- Boy born first
GB- Girl born first
GG

ofcourse it cant be GG, so you are left with 3 different possible outcomes. 3-1

Southpaw
 
Jigger said:
How did you arrive at that PoolBum? Might have fried that corner of my brain containing stat calculations...:p

.5 * .5 * .5 * .5 * .5 * .5 * .5 = .0078125

which also = 1/128

or you can say the probability (P) of something happening n times in a row, if each trial is independent and has the same probability, is P raised to the n power.

.5 ^ 7 = .0078125

Kelly
 
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