## Saturday, October 24, 2009

### Thermometer Trouble

"Life is a Puzzle" is The Math Mom's motto and my favorite puzzles are the ones we encounter in our daily lives and approach bravely and creatively. Here is one of those, inspired by me spending a few days in bed with a cold:

Someone in your household is sick and you would like to take his/her temperature. You find three different thermometers in your medicine closet and ... they all show different temperatures. It is too late to run to the pharmacy and buy a new thermometer. What tricks could you come up with to deduce which of these thermometers may be working correctly and which are failing.
There is no right answer to this life puzzle, but there are few observations or experiments that can help. What would you do to find what thermometer you can trust?

Submit your answer on our Family Puzzle Marathon site. Solve three puzzles and get a prize!

Claire said...

Heck, I would try out all three on myself (or someone who I determined had a relatively normal body temp) and the one that gave the most accurate reading (you know, I dont have a fever, but 2 of those therm. said that I should be dead... what??) would be used on the family member that is sick.

Or stick them in the freezer (since my freezer has the digital temp read-out) and see which one is closest... well, you get the idea.

Maria said...

I like these solutions.
Did not think about the freezer one. Very interesting. I wonder if digital thermometer works in 0 degrees C environment.

Claire definitely get a point here. Her 3rd one! Please email me your address for a well-deserved prize.

Anyone could think of other creative solutions?

prluhmann said...

If one is broke, and two are working, then you could check the temp of anything (like a glass of warm water), and the outlier is the broken one. However, if one is working and two are not, then I think you need a reference point. Claire suggests using a healthy person, but not all healthy people are 98.6 degrees. Perhaps you could place them on your dresser and use the house thermostat as the reference point 9assuming its working). Or place a glass of water on your dresser, and over a couple days it should take on the ambient temp of the room, and once again the thermostat is your reference point. Not trying for a prize, just a suggestion.

Maria said...

I think Claire meant to use a healthy person for elimination of any completely out of range thermometer. Throw them away.

Another trick is to check consistency. Broken devices are frequently inconsistent. Do three measurements on the same (preferable healthy) person with the same thermometer. If readings are drastically inconsistent - throw the thermometer away.

I like prluhmann's and Clair's ideas about comparing with some reference. It may be tricky, as most of the digital body thermometers do not work outside of the expected body temperature ranges [95-110] F. Room and freezer temperatures are way outside this range.

It seems like we exhausted our creativity for now - time for a new puzzle!