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How would you bet?

Other Talk "Otterville" plus Religion/Politics
View Poll Results: What do you do?
$10 on heads
8
25.00%
$10 on tails
9
28.13%
$5 on heads, and $5 on tails
7
21.88%
flip Twikoff to decide
3
9.38%
call the cops
5
15.63%
Voters: 32. You may not vote on this poll

How would you bet?

Old 03-18-08, 04:40 PM
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How would you bet?

The odds of getting heads when you flip a quarter are 50/50.

I have just flipped a coin 99 times, and it has come up heads every time. I am about to flip the 100th time, and I am taking bets.

If you bet heads, and win, you get even money.

If you bet tails, and win, you get double your money.

You have $10 to play, how do you bet, and why?
Old 03-18-08, 04:42 PM
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$5 on heads and $5 on tails. Worst case scenario is I break even.
Old 03-18-08, 04:44 PM
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Tails for double money is the only way to bet here.

Obviously, the first 99 tosses have nothing to do with the 100th, so the odds are still 50/50. Getting 1:1 on your money having the same odds as 2:1 doesn't make sense.

Or, expected value (if my stats hold) of Heads is $0.50 whereas the EV of Tails is $1.00.

In the long run, you're better off betting tails.
Old 03-18-08, 04:45 PM
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Originally Posted by John Galt
$5 on heads and $5 on tails. Worst case scenario is I break even.
Worst case is you lose $5. Best case you break even.
Old 03-18-08, 04:46 PM
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Originally Posted by pinata242
Worst case is you lose $5. Best case you break even.

No, you would start with 10, and end up with 10.
Old 03-18-08, 04:48 PM
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Originally Posted by John Galt
$5 on heads and $5 on tails. Worst case scenario is I break even.
Old 03-18-08, 04:48 PM
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Originally Posted by Mrs. Danger
No, you would start with 10, and end up with 10.
No. If he bets $5 on Heads and $5 on Tails before the flip, he is down $10.

After the flip, there are only 2 outcomes:

1) Heads. He wins $5 on his Heads bet. Net: -$5.

2) Tails. He wins $10 on his Tails bet. Net: $0.
Old 03-18-08, 04:50 PM
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^ Doesn't bet much

You're forgetting to include the initial wager in your winnings.
Old 03-18-08, 04:51 PM
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If it comes up heads 99 times in a row, you probably have a trick coin, so I'd bet on heads.
Old 03-18-08, 04:51 PM
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The odds of getting heads when you flip a quarter are 50/50.

You said you are flipping a coin but not an ordinary quarter.

Odds are, if it has come up 99 times in a row on heads, you are using a double-sided coin. Safe bet is on heads, despite the even odds with a regular quarter.
Old 03-18-08, 04:52 PM
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Shit

It was a long night. Carry on.

I'm not sure who is offering greater than even money on average, though.
Old 03-18-08, 04:52 PM
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Gramps beat me to it. That's what i get for being long-winded.

I think we are both correct.
Old 03-18-08, 04:53 PM
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We win! What do we get?
Old 03-18-08, 04:53 PM
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Take the vegas approach and offer 1.6:1 payout on either heads or tails with the remainder going into a aggregate pot if the coin should just so happen to wind up on its side. Additionally for $.25 more to enter into the growing "jackpot" which would be paid out instantly should the quarter roll away or hit some sort of foreign object thus causing none of the above scenarios to pay out. Void on malfunction.
Old 03-18-08, 04:54 PM
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You guys know me too well.
Old 03-18-08, 05:10 PM
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I'm a gambler and bet on Tails - I would take double my $. on a 50/50 chance.

sort of like when the experts tell you should always use those -match bet- coupons in vegas. I just took away the house odds with my bet.
Old 03-18-08, 05:19 PM
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Assuming I have to bet (I can't just take my $10 and go home) I bet on tails. Each coin flip is a discrete event, so the odds on every flip are 50/50.
Old 03-18-08, 05:25 PM
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i'd say that if you had 99 flips in a row, the odds aren't 50/50. the coin is rigged as others have said
Old 03-18-08, 05:31 PM
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Other. If this were a fair coin, the only answer would be $10 on tails, with an average payout potential of $10. However, the odds of flipping 99 straight sides on a fair coin are 1/2^98 (99 for specifically heads) = 1/3.17 x 10^29. The National Weather Service claims my odds of being struck by lightning this year are 1/700,000. Assuming our interaction lasts 15 minutes, and this being a leap year, my odds of being struck by lightning while watching you flip those 99 heads are 1/700,000/366/24/4 = 1/2.46 x 10^10. The odds of both of us being struck by lightning in that 15-minute window are 1/6.05 ◊ 10^20, which is still around 500 million times more likely than you flipping a fair coin the same way 99 times in a row. I can therefore reasonably assume this is not a fair coin.

Given that, one might be tempted to then bet on heads. However, the mere fact that you approached me with this bet implies you knew this would happen. You can clearly make the coin land on heads, but can you force it to tails? I don't know, so I'll worst case assume that you can. Betting $5/$5 would be pointless, since I already know you can force the coin to heads and will do so to eliminate any loss. Therefore, I'd bet $6 on heads and $4 on tails. Whatever you do, I win $2.

das

Last edited by das Monkey; 03-18-08 at 05:34 PM.
Old 03-18-08, 05:34 PM
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Originally Posted by das Monkey
Other. If this were a fair coin, the only answer would be $10 on tails, with an average payout potential of $10. However, the odds of flipping 99 straight sides on a fair coin are 1/2^98 (99 for specifically heads) = 1/3.17 x 10^29. The National Weather Service claims my odds of being struck by lightning this year are 1/700,000. Assuming our interaction lasts 15 minutes, and this being a leap year, my odds of being struck by lightning while watching you flip those 99 heads are 1/700,000/366/24/4 = 1/2.46 x 10^10. The odds of both of us being struck by lightning in that 15-minute window are 1/6.05 ◊ 10^20, which is still around 500 million times more likely than you flipping a fair coin the same way 99 times in a row. I can therefore reasonably assume this is not a fair coin.

Given that, one might be tempted to then bet on heads. However, the mere fact that you approached me with this bet implies you knew this would happen. You can clearly make the coin land on heads, but can you force it to tails? I don't know, so I'll worst case assume that you can. Therefore, I'd bet $6 on heads and $4 on tails. Whatever you do, I win $2.

das
Old 03-18-08, 05:39 PM
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Originally Posted by das Monkey
Whatever you do, I win $2.

das
Unless I take the money and run!
Old 03-18-08, 06:03 PM
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anyone ever stop to think that the coin might be a trick coin?
Old 03-18-08, 06:12 PM
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Originally Posted by grrrah
anyone ever stop to think that the coin might be a trick coin?
If you had bothered to read das's simplistic analysis...

Originally Posted by das Monkey
I can therefore reasonably assume this is not a fair coin.
Old 03-18-08, 06:48 PM
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Do I get 5:1 if I bet the coin lands on the edge?
Old 03-18-08, 08:12 PM
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