Post:

You have three switches in one room and a single light bulb in another room. You are allowed to visit the room with the light bulb only once. How do you figure out which switch controls the bulb? Write your answer in the comments before looking at other answers.

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If this were an interview question, the correct response would be "Do you have any relevant questions for me? Because have a long list of things that more deserving of my precious time than to think about this!

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[–] otacon239@lemmy.world 202 points 3 months ago (22 children)

For those that want the actual answer:

Tap for spoiler

You turn on the first switch for a minute or two, turn it off, and turn on the second switch. If the bulb is on, it’s obviously the second switch. If the bulb is off and warm, it’s the first switch. If it’s cold, it’s the third switch.

[–] NaibofTabr 248 points 3 months ago (11 children)

This assumes several things to be true, which might not be true:

power is available/the upstream circuit is on (always a bad assumption to make)
the bulb is an incandescent type that will generate an appreciable amount of heat in a short amount of time
the bulb was in the off state before you changed the position of any switches, and has been off long enough to be cold
the bulb is connected to any of the switches
the bulb is connected to only one of the switches (parallel circuits are a thing, as are multi-switch lighting circuits)

If any of the above is not true, the conclusion is invalid.

[–] SmoothLiquidation@lemmy.world 46 points 3 months ago (1 children)

If I asked this question during an interview and the candidate gave me this list of assumptions, I would recommend the candidate. This is exactly what I would be looking for by asking a vague question, not if they memorized the answer to a bunch of riddles, but how they thought and what their line of thought was for troubleshooting the answer.

[–] NaibofTabr 19 points 3 months ago* (last edited 3 months ago)

I tend to agree with this line of thinking. If you're trying to hire an effective problem solver, well the first step to solving any problem is understanding the problem - the whole problem - and often more importantly the context in which the problem exists.

And while my first reaction is to be frustrated with the person asking for a solution to such a vague problem... in the real world problems are rarely clearly stated, and frequently misstated. Investigating the apparent conditions of the problem is always necessary, and generally the fastest path to resolution.

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