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Math help..10 pts for best answer?

The Half-life Kinnium, a radioactive substance, is 1260 years. What percent of a present amount of Kinnium will remain after 300 years?

I can't figure it out..help me please

1 Answer

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  • Anonymous
    1 decade ago
    Favorite Answer

    A(t) = A(t=0) exp(-a t)

    A/A0 = exp(-a t)

    1/2 = exp(-a 1260)

    ln 2 = a 1260

    a = (ln 2)/1260

    A(t=300)/A0 = exp(-(ln 2)/1260 * 300)

    as a percentage:= 100 * A(t=300)/A0 %

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