NetNews Usenet Archive 1992 #20/NN_1992_20.iso/spool/sci/logic/1367

Text File | 1992-09-08 | 1.8 KB | 40 lines

Newsgroups: sci.logic
Path: sparky!uunet!wupost!gumby!destroyer!ubc-cs!alberta!kakwa.ucs.ualberta.ca!access.usask.ca!ccu.umanitoba.ca!silver.cs.umanitoba.ca!sbloch
From: [e-mail] (Stephen Bloch)
Subject: Re: enigma
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Organization: Computer Science, University of Manitoba, Winnipeg, Canada
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Date: Tue, 8 Sep 1992 22:13:39 GMT
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[e-mail] (Marco Bouchard ETUDIANT sept-dec 92) writes:
>You have 10 vending machines to fill out with chocolate bars. In fact,
>after finishing to put the chocolate, you remember that you had 9 boxes
>of chocolate bars of 100g. and one box of bars of 90g and you gotta know
>in which machine you put those of 90g....
>You can weigh as [many]
>bars as you want, but you can take one measure.

[e-mail] (Mark A Biggar) replies:
>Take 1 bar from machine #1, 2 bars from machine #2, ... and 10 bars from
>machine #10.  Weight the whole set of bars.  The expected weight is 5500g.
>But some of the bars weight only 90g, so the actual weight will be some
>number of 10g increments less then 5500g, that number is the number of the
>machine with the 90g bars.

Of course, this approach can be generalized to handle the case in
which you're not sure how many of the boxes were underweight: take 1
bar from machine #1, 2 from #2, 4 from #3, 8 from #4, etc.  Only
problem is, one of the vending machines has to be capable of holding
1024 chocolate bars, and your scale has to be able to handle over 200 kg
of chocolate.  And then there's the question of what to DO with over
200 kg of chocolate... :-)

--
                    Stephen Bloch
                [e-mail]