Coburg Banks | Multi-sector UK recruitment agency

Brainteaser Answer 3

By Mark Wilkinson | Dec 13, 2015 | Staff Retention

A Light-bulb Moment!

Answer 3:  First and foremost, for your own reference, name the switches “a, b and c.”


  • Turn on switches a and b.
  • Wait 10 minutes.
  • Turn switch b off.
  • Enter the room.
  • Whichever light bulb is now on, is controlled by switch a (the only one, still on).
  • Feel the other 2 light bulbs (carefully).
  • Whichever light bulb is warm is controlled by switch b.
  • The cold light bulb must be controlled by switch c.

All you have to do is think outside the box!

- Mark Wilkinson
Mark Wilkinson

Mark Wilkinson

Mark is one of the founders of Coburg Banks and heads up the permanent recruitment division of the business.  Every day he helps companies with their recruitment projects, sourcing the very best individuals for their vacancies.  He understands recruitment inside-out.

> More blog posts by Mark Wilkinson

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