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wu :: forums    riddles    hard (Moderators: Eigenray, william wu, towr, Icarus, ThudnBlunder, Grimbal, SMQ)    scales « Previous topic | Next topic » Pages: 1  Reply Notify of replies Send Topic Print    Author  Topic: scales  (Read 3495 times) Chekov Junior Member     Gender: Posts: 55 scales   « on: Mar 6th, 2007, 9:57am » Quote Modify I dont know if its been done here yet so Ill just put it in. lets c.   You got 12 balls. doesnt matter the size. these 12 all got the same weight. except for 1. you got a scale/balance. The ones they had in the medieval time.     you may use the scales 3 times. then I want to know: - which ball is it that is different - is it weighing more or less then the normal ones   regards, Chekov IP Logged I love riddles.. in the dark (Hobbit) jollytall Senior Riddler     Gender: Posts: 585 Re: scales   « Reply #1 on: Mar 6th, 2007, 11:51am » Quote Modify It is somewhere on the forum (in the easy section).   Just a thought for someone who still wants to solve, rather than search:   There are 24 possible outcomes, and the three measuerement can have 3 outcomes 3 times, a total of 27 cases. So it is not necessarily impossible (actually possible), but don't loose too many cases. IP Logged Aryabhatta Uberpuzzler     Gender: Posts: 1321 Re: scales   « Reply #2 on: Mar 6th, 2007, 11:54am » Quote Modify Probably discussed earlier too..   What if you are only allowed to refer to the results of weighings after you are done with all your weighings.   i.e you cannot use the outcome of the first weighing to determine what you will do for the second weighing etc. IP Logged jollytall Senior Riddler     Gender: Posts: 585 Re: scales   « Reply #3 on: Mar 6th, 2007, 12:07pm » Quote Modify I was wrong: it is in the hard section, since in the original Wu list of riddles it was considered "Relatively Hard": http://www.ocf.berkeley.edu/~wwu/riddles/hard.shtml   (look for 12 Balls).   The thread that discussed it is here: http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_har d;action=display;num=1027806808   I also found a subsequent one discussing it even further: http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_har d;action=display;num=1132320902;start=0#0   Re the subsequent question of Aryabhatta: I am having doubts whether it is possible. Again, as I said earlier you can loose (get redundant results) only 3 times. I am almost sure, without using the earlier results you necessarily loose more. I would look at the permutations of the three measurements to prove that there are more lost cases than 3. IP Logged Aryabhatta Uberpuzzler     Gender: Posts: 1321 Re: scales   « Reply #4 on: Mar 11th, 2007, 8:50am » Quote Modify on Mar 6th, 2007, 12:07pm, jollytall wrote: Re the subsequent question of Aryabhatta: I am having doubts whether it is possible. Again, as I said earlier you can loose (get redundant results) only 3 times. I am almost sure, without using the earlier results you necessarily loose more. I would look at the permutations of the three measurements to prove that there are more lost cases than 3.   I seem to recollect that it is always possible. IP Logged Pages: 1  Reply Notify of replies Send Topic Print Forum Jump: ----------------------------- riddles -----------------------------  - easy   - medium => hard   - what am i   - what happened   - microsoft   - cs   - putnam exam (pure math)   - suggestions, help, and FAQ   - general problem-solving / chatting / whatever ----------------------------- general -----------------------------  - guestbook   - truth   - complex analysis   - wanted   - psychology   - chinese « Previous topic | Next topic »

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