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Sunday, November 22, 2009

Exponential Growth and Credit Cards

This is designed to take a student from reviewing percent change to understanding continuous growth in three days. Probably mostly useful for my NYS peeps, because nowhere else would you be expected to do this in three days. "Days" might be optimistic here. And to paraphrase Moltke, no lesson plan survives first contact with the students. I'll report back after we work through it, after the break. Many thanks to Jake and Dan Greene and my colleague S (who might not want her name published, I don't know), who were kind enough to share their work with me and got whole paragraphs plagiarized for their trouble. (If the formatting on the download looks janky, select all the text and change it to Calibri 11. Use narrow margins.)

(Note: After some revisions a new, improved document was uploaded, and the link changed, at 11:55AM EST on 11/23/09.)

10 comments:

  1. Yikes! I thought the rates you used in the worksheet were unrealistically high. But I'm listening to the NPR show now. Not a pretty picture...

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  2. The default rates! They are crazy! Bananas!

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  3. I like "illegal enterprises and payday loans"

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  4. Day 3 example 3.. shouldn't that be "100% APR"?

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  5. Number 3 that day under "apply your knowledge", I think "at a rate of 16% per day" is misleading. I'd say something like "at a growth rate of 16%".

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  6. Yes that 100% thing occurred to me in a half-awake state last night. Thanks for the proofreading.

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  7. Isn't the "per day" necessary? 16% growth rate doesn't tell you how long it takes the population to increase by 16%.

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  8. But the kids will quickly see that it's *not* 16% per day. The language is really a mess here.

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  9. When I clicked the link it said the file has been removed?

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  10. Awesome. I'm glad to see that Tofu Com Chay made the cut - my favorite vegan restaurant in San Jose! :)

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