<PRE><B>Question 123618</B>
A certain radioactive element decays to 1/2 of its original amount every 20 years. If there was 100mg to start with, how much will be present after 200 years? Set up an equation and solve the problem.
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A(t)=A(0)*(1/2)^(t/20)
A(t) is the amount you have at a certain time.
A(0) is the amount you have when you start.
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A(200)=100*(1/2)^(200/20)
A(200) = 100*0.0313
A(200) = 31.3 mg
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Cheers,
Stan H.</PRE>