I have just placed some money into one of three boxes: a gold box, a silver box and a lead box.  Each box has an inscription.  At least one of the inscriptions is true and at least one of them is false.  The inscriptions are:

Gold box: The money is not in the silver box.

Silver box: The money is not in this box.

Lead box: The money is in this box.

You can only open one box, and if you open the box containing the money you get to keep the cash.  Which box should you open?

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.

76 comments

    1. Yup, unless Richard made a mistake with his inscriptions, or made an untrue statement and put the money in his own wallet, or similar things you can expect from a magician and Richard 😉

    2. At least this one is an easy one as you just have to go thru the combinations, but it sux having people like Moses post the answer after two comments- spoiling it for someone looking for clues. Does Richard ban or at least give a warning to guys like that?

  1. Ok got it – I think. I went through each box and worked out whether the statements would be true or false if the money was inside; only one fulfils the rules.

    1. Isn’t it amazing that there is always some moron that posts their answer within the first 10 posts? You are awesome, Moses! /sarcasm

      Now go find some children and tell them there’s no Santa Claus.

    2. Errp! Replied to the wrong post. Now I’m the moron.

      Oh, Irony, you are an evil mistress.

    1. It’s a shame you didn’t take a few more seconds before posting to read the full instructions, including “As ever, please do NOT post your answers”

    2. As Paul points out, Richard has asked his readers not to share their answers before he reveals the solution on Monday. Additionally, your answer is incorrect, as if the money were in the silver box, all three inscriptions would be false.

  2. If it is as easy as the 3 x 3 matrix then, yep about 20 seconds… but I never know if I’ve missed something!

  3. Think I’ve got it – used a logical process of elimination – now all I need to know is if I am right or just pleased with a wrong answer!

  4. My favourite book “What is the name of this book?” by Raymond Smullyan is full of puzzles like this, including exactly this one (the only difference is it wasn’t money in the box that the inscriptions were clues for) – it’s a great book, I highly recommend it

  5. Surely with the Olympics starting today the boxes should be Gold, Silver and Bronze. I think the money is, therefore, in a concealed bronze box.

  6. I’ve noticed that people have been posting the answer more and more lately. Please could you not do this as it spoils the fun for everybody else. (And if you’re wrong you just look like an idiot.)

  7. That wasn’t too difficult to do – draw up a 3×3 truth table: one answer renders all three clues true, one renders all three clues false, while one renders two clues true and one false.

    However, it would be nice to have the ability to flag / report comments, so we can have an effecitve tool to use against those that don’t read the sentence that immediately follows *every* Friday Puzzle…

    1. Further to the above here is the wikipedia comment on “tertium non datur”
      http://en.wikipedia.org/wiki/Law_of_excluded_middle
      I rest my case.
      It’s Latin for “I am a tw@t”
      PS If it helps I received my degree from Oxford.
      PPS The phase “Sledge hammer to crack a nut” comes to mind” – not that I am a Peter Gabriel fan – he is a tw@t too.
      .

    2. I have one, old boy, which is why I am withdrawing from this thread.
      Don’t let that stop you coming up with a witty response if you want to however.
      Cari Saluti

  8. took me about 10 minutes! first time I’ve tried a ‘Friday puzzle’ so my brain isn’t quite prepared to do these things and struggled…

  9. the real question is whether it’s just one person who keeps posting the answer using different names or if there’s a whole bunch of idiots around these days.

  10. About thirty seconds, to get an answer which contradicted my instinctive one, but which having READ THE ANSWERS EVERYONE HAS ALREADY POSTED I now know to be right. Agree with those requesting a “flag” button, although I don’t suppose Richard has time to spend weeding out the postings of people who can’t be bothered to read the instructions. Perhaps we just have to stop reading the comments until we are each happy with our own answers…

  11. Of course the boxe might nested, which means the money could be in 1, 2 or all 3 of the boxes, re-jigging the order of the nesting might let the 3 conditions remain true for all of these variations. Anyone care to work this out?

  12. I see that I’m not the first to complain about this, but does anyone know why there suddenly seem to be a lot more people posting their answers in spite of Richard’s request not to? I don’t recall it having been a problem before, but I believe it’s happened several weeks in a row. Did Dr. Wiseman’s blog just suddenly shoot up in popularity or something?

  13. @SimonP if the boxes were nested you had no choice but to open the one that contains the others.
    Anyway the best solution is not to open any box, grab the gold one, run away with it, sell its gold and profit from that.

    1. There’s not enough information to evaluate that. How much cash are we talking about? What is the gold content of the gold box? What is the current price of gold on the black market (stolen goods) – is it really more lucrative? Impossible to say. It saves a few seconds’ thinking, which most criminals have problems with anyway, so from that perspective perhaps…

  14. 30 seconds, went the logic route. Somebody needs to smugly post that it’s the remaining box and negate the other two posted answers, at least one of which is ALREADY incorrect! 🙂

    1. The money was always in the pink box, everyone knows that since the dawn of time

      Oh, you said smugly, not smuttily

  15. If you allow one box to be inside another you can get a different answer from what I believe will be the official one.

  16. Between 5 and 10 minutes. Once you see the key statement, it’s fairly easy, but I was slow in finding the key statement!

  17. Took me a couple of minutes, drew a rough truth table and looked at the possible answers that didn’t produce a conflict. I knew maths would come in handy one day 🙂

  18. I’m in the ~30 seconds camp this time, and that includes thinking it through a second time to be sure I’m right.

    so I’m probably wrong 🙂

  19. Oh, I like that one, thanks: rather clever 🙂 Took me about a minute to get it, double-checking just to be sure 🙂

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