Question 622773
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Hi,
A certain radioactive isotope decays at a rate of 0.1% annually.  
Determine the half-life of this isotope, to the nearest year.
 {{{I = I[0]e^(-.001*t)}}}
 {{{ 1/2 = e^(-.001*t)}}}
 ln(.5) = -.001*ln e^t
 ln(.5)/-.001 = t