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)

The answer is 1/3. The statement that at least one shows a tail reduces the original sample space of four outcomes to the following three: TH, HT, TT. Of these, only TT meets the second condition.

Posted by mark hartman on 2003-05-08 19:27:02