Visit my Math for Economists class!

Here is a short video from tonight's Math for Economists class. Here the professor is working an example of an optimization problem with multi-variables and multiple constraints using Lagrange Multipliers. Most of the class is usually theoretical and derivations of theorems, with a few numerical examples. This is one of those cases.



Last week, I mentioned my professor's statement that many mathematicians believe in God or some higher power. Well, tonight as he scrolled up the chalkboard, we found writing from the prior class. This time several Old Testament books of the Bible were recorded: I Kings, Judges, etc. He then told us about a law in Tennessee where they have legislated that pi be equal to 3 (and not 3.14159..) because the Bible states in I Kings that it should be 3. Actually, I Kings 7:23 says the following: "Now he made the sea of cast metal ten cubits from brim to brim, circular in form, and its height was five cubits, and thirty cubits in circumference." So based on this verse it seems the circumference divided by the diameter is 30 / 10 = 3. The professor also referred to a law in Indiana where there was a law setting pi to be 22/7 based on their belief in the Bible. Out of curiosity, I did some searching on the web. This is what I found about the law:

It appears the Tennessee pi law is an urban legend which began as an April Fool's joke in 1998. As for the Indiana law he mentioned, a Pi Bill was proposed in 1897 but never passed. However, it does not appear to be religiously based at all. I couldn't find any evidence of it, anyway. It seems the law proposed either using 3.2 or 4 for pi, not 22/7.

One website I found defended the Bible in I Kings. It says that because pi is 3.14159 that since the circumference was really 30 cubits then the diameter mentioned in I Kings should have been 30/3.14159 = 9.54, not 10. That website claims that the circle's circumference was measured on the inside of the circle but its diameter was measured from the outside of the circle. It says that if the circle had a width of 0.23, the inner diameter would have been 9.54 but the outer diameter would have included the width on both sides, adding 0.46. This would result in an accurate measuremment in the outer diamenter of 10. "Evidence" for this is found in I Kings 7:26 - "It was a handbreadth thick." I'm not sure I buy this explanation though. My guess is that during that time measurements were not so exact plus they probably weren't trying for an exact figure but one that is rounded. Anyway, "pi laws", as far as I know, have never been passed in America. Stories stating so are just urban legends.