Question 1144625: I have six billiard balls, one of which weighs less than the other five. Otherwise, they all look exactly the same. How can I identify the one that weighs less on a balance scale with only two weighings?
Answer by ikleyn(52776)   (Show Source):
You can put this solution on YOUR website! .
(1) First weighting
Put 3 ball to one side of the balance scale and 3 other balls to the other side.
In this way you determine which group of the two is lighter : this group contains the lighter ball.
(2) Second weighting
From the lighter group of the 3 balls put one ball to one side of balance scale and one ball to the other side.
If the scale is in equilibrium, it means that the lighter ball is the third ball of this group.
If the scale is not in the equilibrium, than you can determine which ball of the two on the scale is lighter.
Solved, explained and answered.
It is a classic entertainment problem. Good to develop and exercise your mind from 5 to 75 years.
In this site, you can find other similar problems in the lesson
- Some logic problems
Come again soon to learn something new (!)
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