If A=125e^-kt and A=200 when t=3, find the value of k.
Substitute your known A and t values.
200 = 125 e^-3k
e^-3k = 200/125 = 1.6
Take natural logs of both sides.
-3k = ln 1.6 = 0.470
Solve for k
200 = 125 e^-3k
e^-3k = 200/125 = 1.6
Take natural logs of both sides.
-3k = ln 1.6 = 0.470
Solve for k