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Tennis Ball Problem

Given 27 table tennis balls, one is heavier than the others.
What is the minimum number of weighings (using a two-pan balance scale) needed to guarantee identifying the heavy one? Always. Of course, the other 26 balls weigh the same.

For Solution: Click Here


  1. Hahah !! Why not all the way to 26 ?
    This is a Kinder garden stuff ...

  2. 3 weighings: first is 9 in each pan. If the pans balance, the heavy ball is one of the remaining nine, otherwise it's in the heavier pan. Of the group that contains the heavy ball, weigh 3 balls in each pan tto find the group of three, and then the last weighing has one ball in each pan.