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Path: utzoo!utcs!bnr-vpa!bruce
From: bruce@bnr-vpa.UUCP (Bruce Townsend)
Newsgroups: net.puzzle
Subject: Re: Weighing Problem (solution) and new puzzle
Message-ID: <50@bnr-vpa.UUCP>
Date: Thu, 11-Apr-85 18:51:32 EST
Article-I.D.: bnr-vpa.50
Posted: Thu Apr 11 18:51:32 1985
Date-Received: Thu, 11-Apr-85 20:18:49 EST
References: <322@tekred.UUCP>
Organization: Bell Northern Research, Ottawa, Ontario
Lines: 24

Grab this line, bug...

Ron Bemis seems to claim that it can take up to 7 weighings to
isolate the odd object (and tell whether it's light or heavy)
from a group of 12 otherwise identical objects.

In fact, it can *always* be done in three! I have the solution
if anyone is interested, but the major hint is:

SPOILER***
	Note that three weighings of 4 against 4 (and 4 aside)
have a total of 27 outcomes for the experiment. (Each weighing
has 3 outcomes- tip left, tip right, or balance, and 3x3x3 = 27)
You only need 24 possibilities (one of 12 is either light or heavy)
so label objects 1-12, and discover 3 groupings that will yield
a unique result for each possibility.
-- 
			-Bruce Townsend

			Voice Processing Applications,
			Bell-Northern Research,
			Ottawa, Ontario.

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