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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 re(2): Short solution. | Comment 10 of 12 |
(In reply to re: Short solution. by Jer)

You are right. The 2v2 part is a dead end, left over from something I did earlier, though the odd 4 may still have a role to play.

6v6 is still right, with a slight riff on the theme if the 3v3 balances on the second weighing.

Thanks for pointing this out; you had me worried there for a while, particularly as I'd been told my solution was correct!


Edited on January 12, 2016, 12:07 am
  Posted by broll on 2016-01-11 23:08:08

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