Question 932814
The model must be written, {{{highlight_green(A(t)=700*e^(-0.033t))}}}.  You want to solve for t in {{{1/2=1*e^(-0.033t)}}}.  Take natural log of both sides.


{{{ln(1/2)=-0.033t*1}}}
{{{t=ln(1/2)/(-0.033)}}}
{{{highlight(t=ln(2)/0.033)}}}
21 years