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assume the substance has a half-life of 11 years and the initial amount is 126 grams.How long will it be until only 15 % remains?

  • math -

    1/2 = e^k(11)
    ln .5 = 11 k
    11 k = -.5978
    k = -.05435
    so
    .15 = e^-.05435 t
    -1.897 = - .05435 t
    t = 34.9 years

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