SOLUTION: In the formula A = I^ekt, A is the amount of radioactive material remaining from an initial amount I at a given time t and k is a negative constant determined by the nature of the

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: In the formula A = I^ekt, A is the amount of radioactive material remaining from an initial amount I at a given time t and k is a negative constant determined by the nature of the       Log On


   

Question 1151005: In the formula A = I^ekt, A is the amount of radioactive material remaining from an initial amount I at a given time t and k is a negative constant determined by the nature of the material. A certain radioactive isotope has a half-life of approximately 950 years. How many years would be required for a given amount of this isotope to decay 20% of that amount?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Formula should be A=Ie^(kt), assuming k is negative.

First part, given half life 950 years
1%2F2=e%5E%28950k%29
ln%281%2F2%29=950%2Ak
k=ln%281%2F2%29%2F950
k=-ln%282%29%2F950,
k=-0.0007296
.
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