The guy that solved this riddle is just kidding, right? The question is: "what is the chance that the OTHER coin also came up heads?". The chance that the OTHER coin also came up heads is exactly 50%: tails or heads... :) and it has nothing to do with the state of first coin.
Michael H. Pryor
For the love of all that is good and holy, not this thread again!
Heh. Heh heh heh.
Here's a new outlook (I think -- I couldn't force myself all the way thru the last discussion of probabilities and odds and the superficial distinctions therein). In the statement, "One of them is heads" no distinction is made between the dime and the penny. Therefore, HT and TH are actually the same event, and are contrasted only with HH, leaving a .50 probability. Which also satisfies the obvious feeling that of course there's a 50/50 chance of a heads.
Both coins were already tossed and the results can't change. We know, in advacne, that TT didn't happen.
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