
Lenny D. answered 04/10/19
Tutor
4.8
(563)
Former Tufts Economics Professor and Wall Street Economist
We need e^(rt) = 3 r = .05. so 3 = e^.05t
Take natural logs of both sides and get ln(3) = .05t or t= ln(3)/.05 = 21.97 years