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Circular Balance (Posted on 2008-03-20) Difficulty: 3 of 5
This represents a circular balance.
         o           /|\           o
A light circular disk is needle point mounted. It has a graduated scaled track "o" from which identical measuring pans may be suspended.

Suggest the minimum number of pans as well as the minimum weighings needed, and the strategy required to determine which one of 9 coins is in weight variance with the other 8 in a visually identical collection. You should also be able to determine if the variant coin is lighter or heavier than each of the others.

At the end of each weighing, the coins being weighed will be on the balance, and the balance will be in equilibrium.

For additional discussion:
The set of nine has 7 regular coins with one weighing lighter, and the other weighing heavier than the others.
How might the circular balance assist?
Does a disparate difference in weight of the lighter to the normal than the heavier to normal influence the procedure? [This thought was raised at review.]

See The Solution Submitted by brianjn    
Rating: 2.5000 (2 votes)

Comments: ( You must be logged in to post comments.)
  Subject Author Date
Dej Mar Commentbrianjn2008-04-03 17:59:31
re: Additonal commentary after reading the official solution (Spoiler)brianjn2008-03-29 08:28:31
Some ThoughtsAdditonal commentary after reading the official solution (Spoiler)Dej Mar2008-03-28 12:47:55
An Experimentbrianjn2008-03-27 07:51:15
re: equilibrium? (amendement to solution)brianjn2008-03-27 07:42:57
Solutionequilibrium? (amendement to solution)Paul2008-03-27 02:35:45
re(5): Circular balancebrianjn2008-03-27 01:01:25
Questionre(4): Circular balanceDej Mar2008-03-27 00:01:59
re(3): Circular balancebrianjn2008-03-26 07:04:20
re(2): Circular balanceGamer2008-03-25 22:46:08
re: part 1 solution - some readdressingbrianjn2008-03-25 02:50:03
re(3): Minimum?brianjn2008-03-25 02:31:43
re(2): Minimum?Gamer2008-03-25 01:24:50
re: Equilibrium/extended solutionbrianjn2008-03-21 21:10:42
SolutionEquilibrium/extended solutionPaul2008-03-21 19:50:59
re(2): Minimum?Charlie2008-03-21 09:22:15
re(3): Minimum?brianjn2008-03-21 05:42:04
Questionre(2): Minimum?Dej Mar2008-03-21 05:15:22
re: Minimum?brianjn2008-03-21 01:48:35
Minimum?Gamer2008-03-21 01:25:11
re: part 1 solutionbrianjn2008-03-20 18:58:43
Solutionpart 1 solutionCharlie2008-03-20 12:24:39
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