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Suppose you have two coins which appear identical in your know that one is fair and one is 2 headed.If you take one out,toss it and get a head,what is the probability that it was a fair coin?

$\begin{array}{1 1} \frac{1}{3} \\ \frac{2}{3} \\ \frac{1}{2} \\ \frac{3}{4} \end{array} $

1 Answer

  • Let us define E\(_1\) Taking a fair coin for toss
  • E\(_2\) Taking a baised coinfor toss
  • P(taking a fair coin for toss/getting a head)
  • P(E\(_1\)/A)\(\Large\frac{{p(E_1)}{P(A/E_1)}}{{P(E_1)}{P(A/E_1)}+{P(E_2)}{P(A/E_2)}}\)
since taking any coin for toss in equally likely
P(A/\(E_1\))=P(getting head when fair coins is taken)
P(A/\(E_2\))=P(getting a head when baiased coin is taken)


answered Feb 28, 2013 by poojasapani_1
edited Jun 4, 2013 by poojasapani_1

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