Math CentralQuandaries & Queries


Question from Mary, a student:

Ramon has 6 puppies. Five of the 6 weigh the same and one puppy is heavier. If Ramon had a balance scale, what is the least number of times he could weigh the puppies to be sure he could determine which puppy was heavier?

Hi Mary,

I can see two way to arrange a first weighing.

The first way is to put three puppies on one side of the balance and three puppies on the other side. The second way is to put two puppies on one side of the balance, two puppies on the other side and the remaining two puppies not involved in the first weighing. Whichever of these is your first weighing you can complete the task in one more weighing.

I hope this helps,

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