Tuesday, 17 February 2009

Puzzle Answer

Kongratulations to Zelja for being the only person to have sent in a correct answer to the puzzle! Here is his winning entry:

Answer: 1 minute (for both 60 and 120)
Reason: If you assume that a collision happens when you have one ant travelling “east” and one ant travelling “west” reaching a particular point at the same time, then after the collision there will still be one going “east” one going “west” at the same point, as if a collision had never happened. Therefore the worst case scenario is if an ant starts at one end of the stick, and is going the wrong way, it will take him 1 minute to reach the end of the stick.

The idea was to work out a (sneaky) way to model the ants' bumping into one another, hence why the hint was added later as a little prod in that direction, and also to work out the longest it could possibly take an ant to jump off the stick if unobstructed (which was mentioned in chat). Well done to Zelja for working it out, and thank you to everyone who entered :)

Please leave a comment on whether or not you like puzzles such as these. Perhaps the question was too easy, or 'perhaps' too difficult ;) Maybe this is the first you heard of it and feel it should have been spammed as often as that message that taunts you for not having got the card challenge yet. If you guys liked it then I'll look in my homework for similar questions.

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