math

a radioactive substance decays at an annual rate of 24 percent. If the initial amount of the substance is 640 grams, which of the following functions (f) models the remaining amount of the substance, in grams, t years later?

a) f(t) = 640(0.76)^t

b) f(t) = 0.76(640)^t

c) f(t)= 0.24(640)^t

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asked by lilly
  1. each year, the amount remaining is 76% of the previous year ... 100% - 24%

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    posted by R_scott

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