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A related anecdote: I saw mathematician Andrew Dilnot [1] at a Mathematica users conference a couple years ago, and he asked the audience how many times the siz
by jdleesmiller 14y ago
A related anecdote: I saw mathematician Andrew Dilnot [1] at a Mathematica users conference a couple years ago, and he asked the audience how many times the size of the world economy had doubled since 1900, given that it had grown at about 5% per year. The audience guesses were in the 2-4 range, but he pointed out that the rule of 72 gives 110/(72/5) ~= 7.6. "Don't feel bad," he said, "last week I gave this talk to the council of European finance ministers, and they did no better!" (I may not have remembered the numbers exactly, but they were something like that.)
[1] http://en.wikipedia.org/wiki/Andrew_Dilnot http://en.wikipedia.org/wiki/Andrew_Dilnot
- Locke1689 14y agoYour calculation is way off. You forget that the rule of 72 is how long it takes for the money to double. Thus, the final calculation is 2^7.6 which is, as any good computer scientist knows, a little less than 256
- Tycho 14y agoHuh? At 5% growth per annum, the economy takes 70/5=14 years to double (I prefer the rule of 70). 112 years since 1900, so that's enough time for the economy to double 112/14=8 times.
- adrianN 14y agoThe economy grew by a factor of 1.05^112 = 236. Which is close enough to his number to assume that he missed the "doubling" part of the question. 236 is about 7-8 doublings.
- Locke1689 14y agoWoops, yeah, I thought it asked how many times larger the economy was, not how many times it doubled (which, btw, seems like a weird way to phrase the question to me).
- deleted 14y ago[deleted]