It’s the Friday Puzzle….

52

A man places three coins in front of you – a bronze coin, a silver coin and a gold coin.

The man says “If you tell me a true statement, you will be given one of the coins.  But if your statement proves to be false, you will be given nothing”.

What should you say to guarantee being given the gold coin?

As ever, please do NOT post your answers, but do say if you think you have solved the puzzle and how long it took. Solution on Monday.

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.

52 comments on “It’s the Friday Puzzle….

  1. Cool, I think I just won a golden coin. It took 1min or so but I think that this puzzle reminded me of something quite similar already known, thus, in a certain way, I cheated.

  2. JohnLoony says:

    I think I’ve got an answer that works after about a minute of thinking about it – but I haven’t double-checked all the possible combinations.

  3. G-Man says:

    Some kind of Jedi mind trick might be order “You will give me the gold coin”

  4. The Masked Twit says:

    About a minute.
    Came up with an answer which produced an impasse/loop first.
    This then lead me on to the/(a?) “correct” answer.
    Surprised RW tabled another coin question after all the shennanigans last week.
    Meta.

  5. helgi says:

    Got it in 10 minutes! Not bad for me ;-)

  6. Alex says:

    So far can only guarantee the guy getting rid of a gold coin, but not necessarily you keeping it.

  7. Adzcliff says:

    Blimey, think I got that intuitively in a less than 20 secs. Now to check…

  8. Niva says:

    A very simple one. Thought of a possible answer right away and verified that it works. About 15 seconds.

  9. -M- says:

    I like it, but I still don’t have the answer after quite a while…

  10. elsiem says:

    I *think* I have the answer after just a few seconds of thought, but I know my intuition is often out on these things, so I’m not 100% certain about it, although thinking around it, my answer seems to work from all angles. If I am right I shall spend Monday in an unexpectedly good mood.

  11. Philipp says:

    20seconds to check if my immediate response worked. Knew puzzles like this.

  12. Initially I thought “3 true statements”, but I’ve got the answer now, along Smullyan lines.

  13. first puzzled, then left it, then the answer presented itself as an ‘obvious’ In Wiseman speak I guess my subconsious needed to dwell on it…

  14. Paul Durrant says:

    I got the answer in a couple of minutes thought

  15. Pat says:

    Either I got it in about a minute, or I still haven’t got it ;-)

  16. mittfh says:

    I can think of numerous statements which can guarantee getting one of the coins (“There are two people at this table”, “There are three coins on the table”), but can’t currently work out the logic requiring him to specifically give me the gold coin (assuming it is pure gold and not merely gold-plated steel or iron pyrite!). After all, “You will give me the gold coin” won’t work as it allows him to decide whether to give up the gold coin (thus proving the statement true) or keep the lot (thus proving the statement false)…

    • Bono the noted tax avoider says:

      Here’s another true statement for you – “London is the capital of England”. Hope it helps.
      Paul (just call me Jesus) Hewson

    • ctj says:

      whether it’s pure gold, pyrite, or any other permutation does not matter. also, the* correct statement leaves him no choice but to give you the gold coin.

      i got an answer that works within a few seconds. i’m curious if there are others, but i haven’t been able to think of any.

  17. Anonymous says:

    Got it. Took me a few minutes to get there but I did. (gonna blame it on the fact that I’ve been awake since 3:30 so my brain has decided to fight logic today :) )

  18. Matt says:

    I think I’ve got it after a minute’s thought.

  19. Alistair says:

    I got the solution very quickly but then someone else came up with an alternative. I think mine is better though as their could be ambiguous in certain circumstances.

  20. SofARMaths says:

    Took longer than expected! Several false starts. OK now.
    PS: If you like maths puzzles I have a collection here: http://home.mathsshare.com/Lists/Team%20Discussion/AllItems.aspx. Excuse the Ad! SofARMaths

  21. Istvan says:

    ca. 10 seconds.

  22. Think I’ve got it, but it can’t be that easy… surely?

  23. Bloody American says:

    “I have a gun and anger management issues.”

  24. ChumbleSpuzz says:

    “But if your statement proves to be false…”
    Does this imply that “all” statements must be proved, false or otherwise?

  25. Got it (two or three minutes). Maybe there are more solutions, though.

  26. Duncan says:

    I’m absolutely stumped this time.

  27. Noah F says:

    got it – didn’t take too long.

  28. Laith says:

    I think this one is another where I’m missing a bit of implied info, once I figure that I’ll probably get it quick.

  29. 2 minutes. 1 minute to come up with a question, and another minute to confirm.

  30. Patricia says:

    Definitely got it, in about a minute.

  31. Drew says:

    About 20 minutes. Haven’t worked out any flaws in my logic yet. Really enjoyed this one.

  32. Hoshyar says:

    Solved…. I think !

  33. angel says:

    Always loved your site. Your daily workout for the brain…
    Awesome, I like to share your knowledge.

  34. Anonymous says:

    Could you at least give credit to the original author of the puzzle?

  35. This rings a bell. Aren’t there a lot of puzzles out there similar to this about doors and such? Does the answer begin with the word “If . . . ?”
    I know. I know. I’ve spoiled it for everyone..

    • The Masked Twit says:

      My solution does not begin with if. Nor does it have anything to do with Cretans. I’m not convinced that there is a unique solution to this however.
      TMT

  36. Kristian says:

    Got a solution in a minute or so. But I can’t do it without “and”, making it a 2-in-1 statement. I don’t know if that’s allowed.

  37. TS says:

    I knew what to say after about two minutes, but at that time I had already grabbed all three coins and run away.

    If “A man” comes asking for me, you haven’t seen me, OK?

  38. Almost immediately…

  39. Dharmaruci says:

    i would simple say “give me the gold coin”. that is a true statement, yes?

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