Pre Calculus

If a 25 mg sample of radioactive material decays to 18.4 mg in 5 years, how long will it take the sample to decay to 20.5 mg?

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asked by Brianna
  1. 25*e^-5k = 18.4
    So, k = ln(18.4/25)/-5 = 0.0613

    So, now just solve for t in

    25*e^-.0613t = 20.5

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    posted by Steve
  2. bcx xb

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    posted by Anonymous

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