Puzzle my sister told me about, I've yet to solve it and im open to ideas.
You have 6 balls, 2 red ones, 2 blue ones, and 2 green ones. Out of each pair, 1 is heavy and 1 is light (so overall you have 3 light balls and 3 heavy balls). All the light balls weigh the same. All the heavy balls weigh the same.
You also have a standard set of scales. Your goal is to find out which ball is heavy and which ball is light out of each pair, in just 2 measurements.
First weigh one red and one blue ball against the other red and a green ball. If the scales are in balance, weigh the red balls against each other. If one of the sides is heavier, weigh both red balls against the blue and green ones you used in the first weighing.