Mr. Green, Ms. Orange and Mr. Blue have just returned from a night out when the conversation turns to confirming whether or not Ms. Pink's new "diamond" ring was in fact cubic zirconium. Now, Mr. Blue knows quite matter of factly that there is nothing genuine about Ms. Pink, let alone her ring, but he does not care to be perceived as a Gossip. So the three companions devise the following scheme. Each pair of friends flips a coin in private and records the result. Mr. Green and Ms. Orange flip tails, keeping the outcome hidden from Mr. Blue. Likewise, Mr. Green and Mr. Blue, and Mr. Blue and Ms. Orange secretly flip coins, recording either heads or tails. Each of the three knows the results of exactly two coin tosses--namely the coins that each flipped with the other two--and now reports whether or not the coin tosses resulted in an even or odd number of tails. But there is one twist: If one knows for sure that Ms. Pink's ring is something less than the genuine article, then that individual is instructed to lie about the outcome of the coin tosses. Accordingly, Mr Green reports 'even' (since 2 is even), Ms. Orange reports 'odd', and Mr. Blue--knowing the truth--lies about his coin tosses and reports 'even'. The friends, who know that it is impossible for all three to be telling the truth and still have only one person report 'odd', are shocked by the Truth About Ms. Pink's Ring. Mr. Blue, realizing that the other two cannot determine who lied about the coin tosses, rests easy knowing that his anonymity is intact.
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