The Grey Labyrinth is a collection of puzzles, riddles, mind games, paradoxes and other intellectually challenging diversions. Related topics: puzzle games, logic puzzles, lateral thinking puzzles, philosophy, mind benders, brain teasers, word problems, conundrums, 3d puzzles, spatial reasoning, intelligence tests, mathematical diversions, paradoxes, physics problems, reasoning, math, science.

Ghost Post · Icarian Member

Add one bar from each of the 7 vaults to the scales one by one.
Keep an eye on the change in total weight as you're adding them (If the weight jumps up 10, you've added a real gold bar; if it jumps up by 9 you've added a dodgy bar).
To save effort, you can stop as soon as you've identified 3 dodgy bars and hence the 3 vaults that have been tampered with.

Ghost Post · Icarian Member

Thats a good anwser, but I don't think the authors of the riddle meant for the person to do it that way. Technically each bar you put on is a weighing, so you would potentially be doing 7 at most, and 3 atleast. In order to assume one weighing we can only look at the scale once. You might want to look at some of the other forums.