If I have a jar with 1000 coins and one is double headed and I pick one coin randomly and flip 10 heads what is the probability it is the double headed coin?

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\/ · Accepted Answer

@ Feb 4, You formula is correct, looks like typo. because 2^10=1024 so 1/(1+999/1024) ~= 1/2

(1*1/1000)/(1*1/1000+(1/2^10)*999/1000)

Anonymous · Answer

You can use Bayes to get the real number, which is close to 0.5 (which you can see intuitively) . They wanted the exact number.

Anon · Answer

Shouldn't it be really close to 1 ? Applying Baye's theorem gave me 1/(1+999/2^10) which as I expected will be really close to 1.

V · Answer

Bayes. 10^-3/(10^-3 + 1/2^10 * (1-10^-3))

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