Interesting Probability sum !

instrument.santosh
Posts: 32
Joined: Mon Mar 25, 2013 12:20 pm

Interesting Probability sum !

Postby instrument.santosh » Wed Feb 11, 2015 3:26 am

For all the result-awaiting students (like me ) and all preparing for '15. here is something to get you engaged

A box contains 100 coins out of which 99 are fair coins and 1 is a double-headed coin. Suppose you choose a coin at random and toss it 3 times. It turns out that the results of all 3 tosses are heads.
What is the probability that the coin you have drawn is the double-headed one?

Sanhedrin
Posts: 15
Joined: Wed Dec 11, 2013 11:32 am

Re: Interesting Probability sum !

Postby Sanhedrin » Wed Feb 11, 2015 4:08 am

Bayes' rule:

(1 * 1/100) / (1 * 1/100 + 1/8 * 99/100) == 8/107

instrument.santosh
Posts: 32
Joined: Mon Mar 25, 2013 12:20 pm

Re: Interesting Probability sum !

Postby instrument.santosh » Wed Feb 11, 2015 4:21 am

Yup :D




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