You’re Caught–Stop Your Whining

The King of Freedonia has caught 10 spies from the Kingdom of Sylvania who attempted to poison his wine. The King of Freedonia keeps 1000 bottles of wine in his cellar. The spies managed to poison one of the 1000 bottles but were caught before they could poison any more. The poison is a very special one that is deadly even at one-millionth the dilution of the poisoned wine bottle and takes EXACTLY 24 hours to kill the victim, producing no symptoms before death.

The trouble is that the King doesn’t know which bottle has been poisoned and the wine is needed for the Royal Ball in exactly 24 hour’s time! Since the punishment for attempted regicide is death, the King decides to feed some of the wine to the spies. The King informs his wine steward that he will be able to identify the poisoned bottle by the time the ball starts and kill at most 10 of the spies. Further, each spy drinks only once.

How does he do it?

Problem passed on by Elida Flores, titled by yours truly, phrased by Eric Adelizzi, inspired by Rufus T. Firefly.

(FOR THE EXPERTS: YOU CAN DO IT WITH AT MOST 8 PEOPLE DYING!!!)

Rufus T. Firefly: Awfully decent of you to drop in today. Do you realize our army is facing disastrous defeat? What do you intend to do about it?
Chicolini: I’ve done it already.
Rufus T. Firefly: You’ve done what?
Chicolini: I’ve changed to the other side.
Rufus T. Firefly: So you’re on the other side, eh? Well, what are you doing over here?
Chicolini:
Well, the food is better over here.

34 Comments

  1. Steven Miller on August 4, 2017 at 7:59 pm

    this answer is wrong
    nice idea but cannot do this
    pretend the spy no longer knows which is poisoned as the bottles were shuffled



  2. ANDY PATEL on August 4, 2017 at 7:57 pm

    ASK ONE OF THE SPY TO PICK 999 WINE BOTTLE AND TELL HIM WE GOING TO MIX ALL 999 BOTTLE AND U ALL HAVE TO DRINK WINE FROM THAT MIXTURE.THE LEFT OVER BOTTLE HAS POISON. IN THE NIGHT FEED ALL OF THEM FROM TAHTAT BOTTLE.
    VERY SIMPLE ISNT IT



  3. Steven Miller on January 31, 2014 at 11:55 am

    Glad you enjoy it — tried emailing but it bounced (I’m sjm1 AT williams.edu)



  4. ganhar dinheiro na internet on January 31, 2014 at 5:18 am

    Very good article. I definitely love this site.
    Continue the good work!



  5. Steven Miller on December 20, 2013 at 7:00 pm

    Sorry. I’d suggest some google searching //s



  6. ganhar dinheiro na internet on December 20, 2013 at 6:47 pm

    Great website you have here but I was wondering if you knew
    of any community forums that cover the same topics
    talked about in this article? I’d really love
    to be a part of group where I can get responses from other knowledgeable people
    that share the same interest. If you have any suggestions, please let me know.

    Many thanks!



  7. Steven Miller on September 22, 2012 at 3:51 pm

    dean: correct — email me at sjm1 AT williams.edu



  8. Steven Miller on September 22, 2012 at 3:49 pm

    aryeh: not following your soln — email me at sjm1 AT williams.edu



  9. aryeh on September 20, 2012 at 8:53 pm

    to be a little more detailed if say spies number 1,2,7,8 1 and 10, all drank from bottle number 678, and they are the only that die and there is no other common bottle between the six of them then you know that bottle number 678 is the one.
    Again i am unsure of the mathematical equation.



  10. Steven Miller on September 18, 2012 at 8:56 pm

    sergio: correct! (sjm1 AT williams.edu)



  11. Steven Miller on June 25, 2012 at 4:33 am

    initially it’s to make sure you find the poisoned bottle without worrying about how many spies die, then later we try to minimize the death total.



  12. Viet on June 25, 2012 at 4:27 am

    i dont understand the objective. To save as many bottles or to kill as many spies, or both? Or to save as many spies as possible?



  13. Steven Miller on June 23, 2012 at 3:24 am

    email me at sjm1 AT williams.edu if you want to chat more — I don’t want to give away anything to people reading. ..s



  14. Mike L. on June 23, 2012 at 3:17 am

    Well, you could mix the bottles of wine into ten large portions. The poisoned bottle would ruin 100 bottles and kill one man, but the other 900 bottles and 9 men would be good and healthy. All of them can drink at the same time and you’ll know in the 24 hours time. I don’t know if the idea of being wasteful is problematic, but there is no specification as to how much wine the king’s party needs; besides, 900 bottles of wine is plenty.
    -This assumes you can mix the bottles (or take drops from them so as to leave them in the bottle
    -Another assumption is that no matter what in 24 hours the poison will kill them and that the dilution will not change the time of death (stronger the dose, faster the death).



  15. Steven Miller on April 2, 2012 at 1:39 pm

    I’ll send a hint first.



  16. E on April 2, 2012 at 6:39 am

    I can I have the SOLUTION?



  17. Steven Miller on March 30, 2012 at 6:04 pm

    You want to get it all at once, you don’t want to wait days and days….



  18. scott on March 30, 2012 at 5:40 pm

    dilute small amounts form 100 bottles and serve mixture to a spy, wait 24 hrs and u save 900 bottles, sacrifice one spy and lose 100 bottles, or further dilute that 100 bottle batch to other spies and deduce which one is poisonous



  19. Steven Miller on February 27, 2012 at 6:40 pm

    Depending on how careful / clever you are, you can minimize a bit more the number of spies that might die. Of course, I think they deserve what they get and am not too interested in being more efficient to save them…. The ideas behind this riddle are somewhat related to error detecting and correcting codes. /s



  20. Anonymous on February 27, 2012 at 1:56 pm

    what will be extra credit solution



  21. Steven Miller on February 4, 2012 at 7:30 pm

    Nice try, but the spies used the transporter to get the poison in….



  22. ps on February 4, 2012 at 4:14 pm

    Check for a corkscrew mark to find the bottle, as fine wine would be spoiled after being opened for 24 hours.



  23. Steven Miller on January 17, 2012 at 4:14 am

    The safe generals (if I’m remembering correctly) was more combinatorial. This is a little different (hint: think binary).



  24. Mike B on January 16, 2012 at 8:17 pm

    I don’t yet have a solution for this one, however the approach seems to be the same way that the Safe Generals riddle works. (both tough ones!) Am I on the right track with this plan?



  25. Steven Miller on November 24, 2011 at 1:58 pm

    TWIG: You are VERY close. Email me at [email protected] if you want to talk about the solution (you just have to have everyone drink their mixture simultaneously, not in stages)



  26. twig on November 24, 2011 at 9:01 am

    Note that 2^10>1000. So if each spy drinks drops from half (rounded if needed) of the remaining bottles, we get 500,250, 125, at most 63, at most 32, at most 16, at most 8, at most 4, at most 2, and finally 1 bottle remaining (after each spy has a drink, the number of “uncertain bottles” is halved). So we get find the poisoned bottle.

    Unsure, and have not explained this properly .



  27. Steven Miller on November 7, 2011 at 2:28 pm

    think binary representations — if that doesn’t help email me at [email protected] for a soln



  28. Quess on November 7, 2011 at 8:36 am

    This is tricky !

    Can u give me a hint cause i just cant get it.



  29. Steven Miller on October 19, 2011 at 5:26 am

    too wasteful and takes too long



  30. William Fox on October 19, 2011 at 5:24 am

    Does he need all the bottles?if not you feed 1 drop each from 100 bottles to a spy. You find out but waste 99 bottles.



  31. Steven Miller on July 10, 2011 at 2:06 am

    If you want a hint, email me at sjm1 AT williams.edu



  32. Mark on July 9, 2011 at 1:32 pm

    Fantastic riddle, though I’ve heard it before….probably the hardest riddle I’ve ever come across. I certainly didn’t get it…



  33. Steven Miller on May 23, 2011 at 1:26 pm

    Let me know if you get it or if you need a hint.



  34. Funeral Directors London on May 23, 2011 at 12:38 pm

    Love the brain tease but didn’t have time to complete it. We got as far as they having 200 drops each



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