Interview Question

Product Analyst Interview

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Stockamp & Associates

Problem Solving #2 - You have 3 light switches and 1 light bulb controlled by only 1 switch in a room you can't see into. You can flip any or as many switches as you want and can check the room once. The next time you go into the room, you have to know for sure which switch controls the light bulb.

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Answer #2 - Flip on two switches and check the light. If it is off, you have your answer. If it is on, it is one of the two. Go back to the switches and turn all off. Turn on of the switches on that was on before for about 5 minutes, turn it off, then turn on the other one. When you go into the room, if the bulb is warm but off, it is the first switch. If it is on, it is the second switch. (I didn't get this one right)

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Start with all the switches in the off position. Turn on two of the three switches. when you enter the room the first time, if the light is off, then you know it is the switch you didn't turn on. Else, turn on that switch and turn off one of the switches you previously had on. Now, if the light is off when you enter the room, you know it is the switch you just turned off. If the light is on, you know it is the switch that you had turned on when you looked at the room the first time.

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