Tease Your Brain–Answers
En Español (Spanish Version)

Think a Little Harder...
10. In your cellar, there are three light switches in the ‘off' position. Each switch controls one of three light bulbs on the floor above it. You may move any one of the switches but you may only go upstairs to inspect the bulbs once. How can you determine the switch for each bulb with only one inspection?

Answer: Turn the first switch on for 5 minutes, then turn it off. Turn the second switch on, and leave it on. Don't touch the third switch. When you go upstairs, the bulb that is off, but warm is connected to the first switch, the bulb that is on is connected to the second, and the bulb that is off and cold is connected to the third.








Health Information Library content is provided by EBSCO Publishing, fully accredited by URAC. URAC is an independent, nonprofit health care accrediting organization dedicated to promoting health care quality through accreditation, certification and commendation.

 

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

 

To send comments or feedback to EBSCO's Editorial Team regarding the content please e-mail healthlibrarysupport@ebscohost.com.