Question 1208291
B(t)=B[o]e^(-at)
{{{B(t)=B[o]e^(-at)}}}


(A)
That time length passage was 1 year.

{{{198=200e^(-a*1)}}}

{{{e^(-a)=198/200}}}

{{{e^(-a)=0.49}}}-----------mistake here

{{{cross(a=-ln(0.49))}}}

{{{cross(a=0.713)}}}