Answers>Oxbridge Preparation>Mentoring>Article

A windowless room contains 3 light bulbs, each connected to a switch outside the room. You can flip any of the switches in any order. You can then enter and look at the lights, but not touch the switches again. Which switch controls which light?

Flip on switches 1 & 2, wait a moment and switch off number 2. Enter the room. Whichever bulb is on is wired to switch 1, whichever is off and hot is wired to switch number 2, and the third is wired to switch 3.

Answered by Emily F. • Oxbridge Preparation tutor

3553 Views

A windowless room contains 3 light bulbs, each connected to a switch outside the room. You can flip any of the switches in any order. You can then enter and look at the lights, but not touch the switches again. Which switch controls which light?

Related Oxbridge Preparation Mentoring answers

If the State could ensure all criminals were convicted 100% of the time, but at the cost of the total loss of privacy of all other civilians, would it be justifiable?

There are four prisoners in a line with a brick wall separating them to three and one. They are wearing alternative coloured black and white hats, but they do not know this. They only see ahead of them - which prisoner can solve the colour of their hat?

What is the most important thing to do in the interview?

Do we have a moral obligation to protect the weak globally?

We're here to help

Company Information

Popular Requests

© MyTutorWeb Ltd 2013–2025

CLICK CEOP