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Math Help - Decay rates

  1. #1
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    Decay rates

    I'm having second thoughts on the answers I came up with...

    Einsteinium-235 decays at a rate of 3.406% per day.

    a. find the annual decay rate in exact form:
    100(.96594)^365

    b. Compute an approximation of your solution in part a accurate to two decimal places:
    (This is where I was thrown off, as my equation truncated to two decimal places comes out to be 0.00, and I'm sure that's not the intention.)
    3.21 x 10^-4

    c. Find the half-life of Einsteinium-235 in exact form:
    100(.96594)^t=50
    log(96.594^t)=log(50)
    t x log(96.594)=log(50)
    t=(log(50))/(log(96.594))

    d. Compute an approximation of your solution in part c accurate to two decimal places
    0.85
    (But I know that's obviously wrong. )

    Any help appreciated.
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  2. #2
    Eater of Worlds
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    Half-life can easily be gotten from the formula

    k=\frac{-1}{T}ln(2)

    k=ln(.96594)

    You know k, enter it in and solve for T.
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  3. #3
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    What about my decay rate?
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  4. #4
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    That's k.
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