perplexus.info :: Weights and Scales : One of Sixteen

One of Sixteen (Posted on 2015-12-29)

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.)

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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