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-   -   I flipped 100 coins (http://archives1.twoplustwo.com/showthread.php?t=548815)

markuisis 11-18-2007 08:32 PM

Re: I flipped 100 coins
 
[ QUOTE ]
[ ] Would like to meet OP

[/ QUOTE ]

It would be quite an honour

traz 11-18-2007 08:36 PM

Re: I flipped 100 coins
 
awesome imo

valenzuela 11-18-2007 08:38 PM

Re: I flipped 100 coins
 
This thread made my day

sh58 11-18-2007 10:03 PM

Re: I flipped 100 coins
 
i just flipped a 2 pound coin (cos i'm a baller) and it landed on heads.

Pokey 11-18-2007 10:05 PM

Re: I flipped 100 coins
 
[ QUOTE ]
Okay I've got a math question I was thinking about recently but am not smart enough to figure out my self (plz don't make fun if it's really easy).

Let's say I play blackjack and I am 49% to win every hand. If I played blackjack every weekend for 2 hours for the rest of my life, what would my chances at being a winner at the end be (if you need the figures, which you probably don't, let's assume I average 50 hands per hour and play 4000 hours in my life)?

I guess the answer is 49% but that doesn't seem right.

[/ QUOTE ]

Hey, I'm feeling a bit mathy, so I'll go ahead and answer the question.

To make the math easier (without really skewing the results much), let's say you either win $1 or lose $1 in each hand. There's a 49% chance you win a buck and a 51% chance you lose a buck. This gives us a nice binomial distribution which is very easy to manipulate and evaluate.

Over your lifetime you'll play 4000x50 = 200,000 hands of blackjack. In the average 100 hands you'll win $49 and lose $51, so your expectation is -$0.02 per hand, for a lifetime expectation of -$4,000. Now the variance of your lifetime total is going to be about 2*n*p*(1-p), or 2*(200,000)*(0.49)*(0.51) = 99,960. To find the standard deviation we take the square root of this number, giving us a standard deviation of about $316.16. To have a lifetime win, you'd therefore have to beat your expectation by 4000/316.16 = 12.65 standard deviations. Since there is a roughly 99.99999999974% chance of being within 7 standard deviations, the odds of you being a lifetime winner at blackjack are going to be markedly worse than that. I'd say the odds that you win at blackjack over your lifetime are slightly worse than the odds that you get hit by two meteors at the same time.

Nielsio 11-18-2007 10:12 PM

Re: I flipped 100 coins
 
[ QUOTE ]
I'd say the odds that you win at blackjack over your lifetime are slightly worse than the odds that you get hit by two meteors at the same time.

[/ QUOTE ]


So you're saying there's a chance?

Unknown Soldier 11-18-2007 10:35 PM

Re: I flipped 100 coins
 
ofc theres a chance

ajmargarine 11-18-2007 10:44 PM

Re: I flipped 100 coins
 
[ QUOTE ]
I'd say the odds that you win at blackjack over your lifetime are slightly worse than the odds that you get hit by two meteors at the same time.

[/ QUOTE ]

But dude, I win at blackjack. I has a system.

jfish 11-18-2007 11:14 PM

Re: I flipped 100 coins
 
haha somebody linked me to this. nielsio you have 10k+ posts. seriously?

Demogorgon 11-18-2007 11:16 PM

Re: I flipped 100 coins
 
Seriously you need to do it with 10 000 flips to see if you get closer to 50/50 - It will give us an entirely new view on variance.


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