I toss two coins and look at the outcome. I then tell you that at least one of the coins is showing up as "tails". What is the chance that the other one is showing "tails" as well?

(from techInterview.org)

(In reply to re(3): Question On The Solution by Matt)

Matt, you are right in recognizing the wording of the problem is not quite correct.  As it is written, the probability is 1/2. 

If the narrator said:  'I toss two coins and look at the outcome. I then tell you that at least one of the coins is showing up as "tails". If you are to take one of the coins, what is the chance that the one you have taken is "heads"?', then, I believe, the probability may be the 1/3 that was expected in the solution.

Posted by Dej Mar on 2007-10-25 00:58:34