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5 Wood-cutting Machines

Logic puzzles require you to think. You will have to be logical in your reasoning.


Puzzle ID:#18843
Fun:*** (2.29)
Difficulty:*** (2.83)
Submitted By:nenad**
Corrected By:Nytwynd




In a wood-cutting factory, five large sawing machines stand in a windowless room. Each machine has an on/off switch attached, there being no doubt as to which switch controls which machine. Outside the door to the room are five back-up on/off switches, one for each machine inside. The power for each machine must first pass through the back-up switch, and then the machine switch before reaching the saw. The problem is, the new manager cannot decide how these back-up switches match with the machines inside the room. One day, the manager's brother visits. The manager takes him inside the sawing room where all five machines are at work and explains the problem. The brother announces that he intends to leave the room and that when he returns he will be able to match correctly the five switches outside the room to the five machines inside. The brother works alone, cannot see the machines from outside the room and solves the problem purely by operating switches. How is it possible?

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Sep 20, 2004

It may seem obvious that the machines generate heat, but that should be a clue. Other than that great teaser
Sep 26, 2004

How about this? Not sure what kind of saws these are, but if they can automatically cut wood, you could start 5 new pieces of wood at the same time, one on each machine. Then go outside, and shut off each switch, 30 seconds apart. When you come back in, the switch you turned off first will have the shortest cut, the second switch would have the next to shortest cut, and so on.

Mar 07, 2006

One of the top 5 I have seen here so far.

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