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Home > Logic > Weights and Scales
Circular Balance (Posted on 2008-03-20) Difficulty: 3 of 5
This represents a circular balance.
                       
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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: ( Back to comment list | You must be logged in to post comments.)
re(3): Minimum? | Comment 6 of 22 |
(In reply to re(2): Minimum? by Dej Mar)

Let me address your second sentence in your response. 

I believe that the mechanics of this "device" have been given by way of its central pivot
and
"It has a graduated scaled track "o" from which identical measuring pans may be suspended."
In its state of void it is in equilibrium.

I am tempted to be definitive, but you have actually asked the questions which contain the words/concepts that you seek.

I have a feeling that Charlie may have had a whimsical moment by not fully divulging all that he was seeing.  But then in review he questioned 'weighings to pans as minimal' which Gamer has taken up.

Look to Charlie's commentary.





  Posted by brianjn on 2008-03-21 05:42:04

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