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Home > Logic > Weights and Scales
One of Sixteen (Posted on 2015-12-29) Difficulty: 3 of 5
I have two sets of 8 coins. In one set the coins weigh 30g each, in the other set the coins weigh 31g each.
Unfortunately they got mixed together in one big pile of 16 coins. I want to identify one coin. It can be from either set.

(Easy) Using a balance scale, identify a coin in four weighings.

(Hard) Identify a coin in just three weighings.

See The Solution Submitted by Brian Smith    
Rating: 4.0000 (3 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Some Thoughts Easy does it | Comment 1 of 12
I haven't played with this, but the easy method is pretty clear.  I don't offhand see the hard method.

My prediction:

The easy method is "superior" in that:
a) It is simpler to do
b) The expected number of weighings with the easy method is lower

  Posted by Steve Herman on 2015-12-29 13:45:30
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