SOLUTION: An initial amount of a radioactive substance y0 is given, along with information about the amount remaining after a given time t in appropriate units. For an equation of the form y

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Question 1032480: An initial amount of a radioactive substance y0 is given, along with information about the amount remaining after a given time t in appropriate units. For an equation of the form y = y0ekt that models the situation, give the exact value of k in terms of natural logarithms: y0 = 2.56 lb; After 2 yr, 0.64 lb remains.
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
y=Ie%5E%28kt%29, changed y sub 0 to I for easier typing of text;

ln%28Ie%5E%28kt%29%29=ln%28y%29
ln%28I%29%2Bkt%2Aln%28e%29=ln%28y%29
kt%2A1=ln%28y%29-ln%28I%29
highlight%28k=%281%2Ft%29%28ln%28y%2FI%29%29%29

Substitute the given values and evaluate.