intellegent-
I think the answer to your “train” riddle is 25:
One on the hour * 13 + one on the half-hour * 12
Joseph-
Cryptograms are logic puzzles, but they take a while, so I’m skipping them for now.
Your “brain wave cd” puzzle was asked by Feivel on the first page of this thread, in a different format (if there are multiple CDs per box). If there is only one CD per box, you need three or four tries, depending on how lucky you are.
The “15 gold pieces” solution is three. Split the pieces into three groups of five (lets call them x, y and z), and compare x vs. y.
Split the group thay is lightest into three groups of two, two and one (lets call them za, zb and zc).
Compare za vs. zb.
If they are equal, zc is the exception, otherwise split the group with the exception and perform one more compare.
Gut voch.