I have three coins, like the coins from Fifty-fifty. The first coin is a regular coin with heads and tails sides; the second coin has heads on both sides; the third coin has tails on both sides.

Two coins are chosen and flipped, with the third still shrouded in a pouch. The results of the flips shows one head and one tail. What is the probability that the normal coin is the coin still in the pouch?

(In reply to Solution (spoiler) by Steve Herman)

Baye is always right (although not always easy to see).

With good coin in purse, there are four combinations (out of four) that will produce [H/T].  With good coin on table, there are four combinations (out of eight) that will produce [H/T].

Well done, Mr. Herman.

Posted by hoodat on 2017-06-15 12:46:35