# math

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A material has a half-life of 12 hours. If initially there are 4 grams of the material, how much is present after 8 hours?

• math -

no need for calculus.
the amount left after t hours is

4 (1/2)^(t/12)
when t=8, that is
4 (1/2)^(2/3)
= 2.52

I think the 8/3 = 2.67 answer is bogus. Close, but nowhere near exact. 8 is 2/3 of 12, but that's not how half-lives work.

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