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Math Help - Radioactive Decay...Part 2

  1. #1
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    Radioactive Decay...Part 2

    Iodine 131 is a radioactive material that decays according to the function A(t) = A_0(e)^(-0.087t) where A_0 is the initial amount present and A is the amount present at time t (in days). Assume that a scientist has a sample of 100 grams of iodine 131.

    Note: A_0 is read: "A sub zero"

    (c) When will 70 grams of iodine 131 be left?

    (d) What is the half-life of iodine 131?

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  2. #2
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    part a: 70=100e^{-.087t}, solve for t.

    Half life can be gotten from T=\frac{-1}{k}ln(2)
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    your formual...

    What does upper case T and lower case k stand for in your half-life formula?
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    k is the decay constant.

    T is the half life time.

    So, your half life would be \frac{-1}{-.087}ln(2)\approx 7.97
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    But...

    But I want to know what numbers do I replace k and T with in the half-life formula you shared.

    Thanks
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