It's time for a new riddle, but first let's take care of the last one (http://omer-behindthelines.blogspot.com/2008/07/riddle-2-grand-slam.html).
The key to this riddle is the fact that after each game exactly one player leaves the tournament. Since we must have a single player that is left in the tournament and wins it, all the other players must lose, each one in a different game. Therefore, if we have 8192 players, it will take 8191 games to lose all but one players. As you can see, the math needed here was very very simple, as opposed to adding up the number of games in each round...
Riddle 3
In this riddle we have a stick. This stick is exactly 1 meter long. It is a known fact that an ant walks on this stick at exactly a speed of 1 meter per minute. It is also known that once an ant starts to walk in a given direction (left or right) it will continue to do so until she drops of the stick or until she meets another ant. 
So far we can say that if we drop one ant on the stick, no matter where we drop it and to what direction, the ant will fall from the stick after 1 minute or less.
In the case of an ant meeting an ant, each one jumps around to the opposite direction and continues to walk (see diagram below). This meeting and jumping does not take anytime what so ever.
The question is, if we drop 1000 ants on the stick and each ant randomly picks a direction from its random dropping point, how much time (maximal) do we need to enable all the ants to fall off?
P.S. again - this is a logic question and there is no need to get into complicated math.
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5 comments:
Hi Omer
Assuming that ant does not have dimension (1000 ants on 1 meter stick?), it will take less than 2 minutes for all of them to fall down.
First of all, you are right about assuming that the ants themselves do not have a dimension - they can all be placed on a 1 meter stick, and we even assume that each one was dropped in a different place on the stick (and no ant is on an other ant's back).
Secondly - your answer is correct but it is not the best answer. What I mean is that they will fall down in less than 2 minutes, but the best answer is that they will fall within X seconds - less than 120...
1 minute - the ants might as well continue in their direction since they merely change places with each other
Yeah, i agree with amir - its like they just walk past each other
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