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
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?
2 answers
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2 answers