Browsing the archives for the bulb tag

Three Switches

Question: You are standing outside a room next to three switches, all of which are off. Each switch operates a different light bulb in the room. The room door is closed, so you cannot see which switch operates which bulb. You are only allowed to go into the room once. Determine which switch operates which […]


Bulb Or No Bulb?

Question: There are 100 bulbs arranged in a row. Each bulb has its own switch and is currently turned off.  In the first round, you turn every switch on. In the second round, you flip the switch of every second bulb (i.e. bulb 2, 4, 6, 8 and so on). In the third round, you […]

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