t=-In(0.24)/0.00012

Answer 1

t = - ln 0.24 / 0.00024

t = - (-1.427116356) / 0.00024

t = 5,946.318149

Answer 2

t = -ln(.24)/.00012

t = about 1.427/.00012

t = about 11,892.64 years (or days or whatever the unit of time was in the problem)

t =11892.64/365.25

t = 32.56 years if t was measured in days

t then would = 32 years 6 months and about 22 days

A = Pe^rt is the general formula for continously compounded interest or continuous growth or decay

A/P = e^rt

ln(A/P) = rt

t = ln(A/P)/r where r = rate of decay if A/P <0

this problem looks like a negative growth or decay problem