Plan: answer homework questions. Then I need to say something about compounding and the formula (1+r/n)^n. But simply calling that APR is wrong. APR/EPR is much more complex, and does not always mean the same thing. (The wikipedia article is pretty convincing on that point.) Maybe just do the payday loan example from the book. The real ten year takeaway is, as usual pay attention!
I’d like to get on to probability. It’s a nice change of pace. Perhaps I can do the easy stuff (just counting), so the decks will be cleared for gambling next week. If I decide not to get to money today then I might want to change the order of topics from the book and do repeated events, preparing the way for independence.
Interesting class. I didn’t do anything like what I’d planned. Started by working the Chinese R&D expenditure problem. I thought that starting with the exponential growth spreadsheet would be the best strategy, but in fact just working backwards fom $70 billion by multiplying repeatedly by 0.8 was better: quicker and more instructive.
I was ready to move on to probability when I realized I’d said nothing about doubling times and half lives. So we discovered the rule of 70, I told them they’d need ideas from calculus to understand why it was try. Having discussed doubling times I moved on to half lives. That called for an explanation of radioactivity – and a discussion of the chemistry and the history of nuclear bombs and nuclear power. I did the talking, the students were all ears. None of that will be on the exam but it will probably stick with them for years …
Probability next week.
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