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A weighing problem


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7 replies to this topic

#1 BMAD

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Posted 19 November 2013 - 06:00 AM

Nine identical looking cubes but two off by 1 gram (the two not necessarily equal to each other).  However the cubes have a particular trait, when numbered they magically gain the weight of the number written on them.  Without numbering there is no physical way to distinguish one cube from the next.  You were hired by the owner of the nine cubes to number the cubes in such a way that the two cubes different from the others can be identified easily.  

 

To assist with finding the cubes you have a balance scale and a marker.  What is the least number of weightings needed to find the off cubes and what will be your numbering system?


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#2 BMAD

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Posted 24 November 2013 - 03:38 PM

Usually weighing problems get more attention then this :(
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#3 TimeSpaceLightForce

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Posted 28 November 2013 - 08:38 PM

If i mark one with a dot ..will it gain 1 gram?


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#4 phil1882

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Posted 28 November 2013 - 10:10 PM

fairly straigth froward to do it in 4 if all numbers are same value

hte question is can it be done in 3 with different numbers?


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#5 BMAD

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Posted 29 November 2013 - 02:12 AM

Yes @tslf. Any system that denotes 1 results in 1 extra gram and per the op, you can only number them

Edited by BMAD, 29 November 2013 - 02:12 AM.

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#6 plasmid

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Posted 29 November 2013 - 05:33 AM

Spoiler for

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#7 BMAD

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Posted 29 November 2013 - 04:24 PM

@plasmid  That is a brilliant idea!  But I intended for the OP to imply only positive gains as a negative gain is not a gain in this context.


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#8 TimeSpaceLightForce

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Posted 01 December 2013 - 05:59 PM

Spoiler for


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