# Lightbulbs and switches

### Lightbulbs and switches

Suppose we have 50 light bulbs in one room of a big house and 50 switches at a switchboard close to the entrance, far away from the room and without visual contact with it. Each of the switches corresponds to one light bulb. We can only see the status (on, off) of each light bulb by walking to the room.
We want to find out which switch goes to each bulb. What is the minimum number of times we will need to walk to the bulbs room?

I don't know how to solve these types of problems but I assume it has to do with divisors and modulos of 50.
Any clues?

Guest

### Re: Lightbulbs and switches

6 times because 2^6=64>50.

Alex.vollenga

Posts: 8
Joined: Wed May 17, 2017 10:04 am
Reputation: 2

### Re: Lightbulbs and switches

Assume each switch is individually wired to control only one switch.
He will not know which switch control which light except each switch is operated and the actual light is verified.
Even when 49 switches are verified he cannot just assume the 50th switch controls the 50th light, so he will also have to switch the 50th switch.
So the answer is 50 times to verify each switch and light pair.

Guest

### Re: Lightbulbs and switches

Assume each switch is individually wired to control only one switch

That should have been....Assume each switch is individually wired to control only one light.

Guest