Humans—smart enough to have ideas; foolish enough to believe them
weigh 1, 2, 3, 10 vs. 4, 5, 6, 111, 2, 3, 11 vs. 7, 8, 9, 101, 4, 7, 10 vs. 2, 5, 8, 12
Once you you've done those weighings, how do you decide which is the bad coin?
each coin is in a unique group of weighings.1 is in left, left, left2 is in left, left, right3 is in left, left, none4 is in left, right, noneetc.Also no opposite pattern to any of these is taken.So if the scales tipped left, left, left you'd know 1 was heavier.If it was the opposite, right, right, right, then 1 was lighter.
whoops, 4 is left, none, right.
Thanks. I guess Google knows everrything. Here are two sites that discuss this problem in detail. http://www.iwriteiam.nl/Ha12coins.html gives the answer above along with some others. http://www.cut-the-knot.com/blue/weight1.shtml gives other solutions.
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