Of 12 coins in a bag 1 is counterfeit and weighs less what is the least weighings to determine the counterfeit?
please explain your answer
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Are you using a number scale or an equal side scale?
If a scale where one side is weighed against the other the answer is three.
1. First weigh six coins vs. six
2. Take the lighter six and weigh three vs, three
3. Take one coin from each of the lighter three and weigh them. If they are the same, the one not weighed is counterfeit. If different the lighter one is.
If you’re using a weigh scale it’s six weighings.
1. 2 weighs for step 1 above
2. 2 weighs for step 2.
3. 2 for step three. You might get the counterfeit first time but wouldn’t know it.
You only need TWO weighings.
Answer is coming pretty soon
OK my bad it’s 3 ^^ :
1) Take a first weight 4 vs 4 (and 4 on the side)
2) Choose in the 4 less weighted 2 vs 2
3) Then 1 vs 1.