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The Great Weights Puzzle

Age 14 to 16
Challenge Level

This problem follows on from 9 Weights

You have twelve weights, one of which is heavier or lighter than the rest, but you don't know which one is heavier or lighter, and a balance. Using just 3 weighings on the balance, can you find a way to identify which weight is the odd one out, and whether it is heavier or lighter?