You have seven coins, one of which weighs less then the others and it cannot be told by their appearance. You are given a balance scale and can only use it twice. Determine how to find out which penny is the lightest.
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You have seven coins, one of which weighs less then the others and it cannot be told by their appearance. You are given a balance scale and can only use it twice. Determine how to find out which penny is the lightest.
I got to see your post today. I will keep three aside and weigh the other four( two per side of scale). A tilt will make me weigh the two coins that has less mass to determine one that is lighter. If there is no tilt. I will weigh two coins from the ones I kept out from the initial trial. If there is a tilt. Then I have mine answer, if there is none, then the coin that I didn't weigh is my answer(the lightest).