SOLUTION: Suppose a quantity is halved every 18 years. Use the approximate half-life formula to estimate its decay rate.

Question 445768: Suppose a quantity is halved every 18 years. Use the approximate half-life formula to estimate its decay rate.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Suppose a quantity is halved every 18 years. Use the approximate half-life formula to estimate its decay rate.
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A(t) = Ao*e^(-rt)
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(1/2)Ao = Ao*e^(-18r)
--
e^(18r) = 1/2
-18r = ln(1/2)
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r = [ln(1/2)]/(-18)
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r = 0.0385 or 3.85%
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Cheers,
Stan H.
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