Crazy Math

  As you know, I've been traveling and currently I am in San Juan, Puerto Rico for a conference.  The conference is almost over and I'll be hitting the road again, heading for Washington state.

In the math classes, I stress using all one system of measurement to make sure all units are consistent but I got a shock the other day on the way out to the radio telescope in Aerocibo, Puerto Rico.

As the bus traveled on the toll road, I noticed all the markers along the side of the road were in kilometers.  We use them to check mileage along any road so if we have to call in for assistance, we can tell them we are at mile 35.7 or at kilometer 22.3.  Signs showing the distance to the next town are also in kilometers but the speed limit signs are in miles per hour!

You read that right. Speed limits are in miles per hour which can make things really confusing.  I had to ask to make sure it was miles per hour and not kilometer per hour because the posted speed limit was 65 and 55.  No unit designation on it.

The guy sitting next to me on the bus was as confused as me when we saw those numbers.  Although, Puerto Rico is a territory of the United States, it mixes English measurement with metric.  For instance, gas is sold per liter while tomatoes are per pound.  My taxi driver tried to tell me gas was only $1.29 per gallon yet sold for 60 cents per liter.  I don't think he knows the real conversion rate.  He also said each gallon has 5 liters.

I checked out some real estate adds for houses in the area.  The main unit is meters squared with some translation into standard measurements but I'm not sure if the unit is for the house or the land.  That part wasn't that clear.  I did not watch any local television stations so I do not know if temperatures are given in Celsius or Fahrenheit. 

When school starts in the fall, I can share the unique mix of systems with my students.  I plan to take time to explain how confusing it was to see things in one or the other or both depending.  This is the first place I've ever been where I've seen both systems used. 

Let me know what you think.  Puerto Rico appears to be the exception to the rule.  Have a good day and enjoy yourself.