The 8 Coins and 2 Weighings Balance Scale Riddle
You have 8 identical-looking coins, one heavier than the rest. Using a balance scale (no weights) in exactly 2 weighings, what first step guarantees you identify the heavier coin?
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What is the answer to the 8 coins, 2 weighings riddle?
Place 3 coins on each pan and leave 2 aside. If the pans balance, the heavier coin is among the 2 set aside, so weigh those two against each other. If one pan drops, the heavier coin is in that group of 3, so weigh any 2 of them: the heavier shows, or it's the third.
Why split the 8 coins into groups of 3, 3 and 2?
Each weighing has three possible outcomes (left down, right down, or balanced), so two weighings can distinguish up to 9 cases. Splitting into near-equal thirds lets a single comparison eliminate most coins at once, guaranteeing the answer in exactly 2 weighings.
Is this coin riddle easy or hard?
It's a hard logic riddle. The trick is realizing a balance scale gives three outcomes per weighing, not two, so you divide the coins into thirds instead of halves.