Question 1192687
{{{y=Ae^(-kx)}}}
-

If using the description for this model, then A=100, y=13 but first need a value for k.
Half-life information means if A=100 and y=50, then  {{{50=100e^(-5730*k)}}},
{{{1/2=e^(-5730k)}}}
{{{ln(1/2)=-5730k}}}
{{{ln(2)=5730k}}}

{{{k=ln(2)/5730}}}
{{{k=0.00012097}}}


{{{highlight_green(y=Ae^(-0.00012097x))}}}


How long ago the tree died?
{{{ln(y)=ln(A)-0.00012097x}}}

{{{ln(y)-ln(A)=-0.00012097x}}}

{{{ln(y/A)=-0.00012097x}}}

{{{highlight_green(x=(ln(y/A))/(-0.00012097))}}}

{{{x=-ln(0.13)/0.00012097}}}

{{{highlight(x=16900)}}}