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Guest Message by DevFuse

# The probability of a bad coin

Best Answer plasmid, 28 April 2014 - 04:14 AM

In that case, I'll go ahead and just say what I consider the answer to be.

Spoiler for
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Posted 23 April 2014 - 03:25 PM

If you flip a coin n times and you get n-1 Tails from those flips, what is the probability that the coin is biased?

Edited by BMAD, 23 April 2014 - 03:27 PM.

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### #2 bonanova

bonanova

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Posted 27 April 2014 - 05:17 AM

Spoiler for First thoughts

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The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell

### #3 plasmid

plasmid

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Posted 27 April 2014 - 04:08 PM

Spoiler for a hint (if my understanding of the question is correct)

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Posted 28 April 2014 - 12:56 AM

hmmm you may both be right.  I was asked such a question and couldn't answer myself.

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### #5 plasmid

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Posted 28 April 2014 - 04:14 AM   Best Answer

In that case, I'll go ahead and just say what I consider the answer to be.
Spoiler for

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### #6 plasmid

plasmid

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Posted 28 April 2014 - 04:24 AM

Alternatively, you could just do what biologists do. Calculate a p value, and if it's less than 0.05 then consider that to be proof that the coin is biased. I think p<0.05 for n>7 based on bonanova's formula.
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### #7 bonanova

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Posted 28 April 2014 - 04:25 AM

Yeah. What he said. Prior ... Something.
Bushindo explained Bayes to me once before, plasmid just did again,
but it's still not something I could explain to my grandson.
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The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell

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