Answer: 28.43 years
Step-by-step explanation:
[tex]A = P(1 + r)^t\quad \text{where}[/tex]
[tex]12,200=400(1+0.04)^t\\\\3.05=(1.04)^t\qquad \rightarrow divided\ both\ sides\ by\ 400}\\\\ln(3.05)=ln(1.04)^t\rightarrow applied\ natural\ log\ (ln)\ to\ both\ sides\\\\ln(3.05)=t\ ln(1.04)\rightarrow applied\ log\ rule\ to\ eliminate\ exponent\\\\\dfrac{ln(3.05)}{ln(1.04)}=t\qquad \rightarrow divided\ ln(1.04)\ from\ both\ sides\\\\\\28.43=t\qquad \rightarrow used\ calculator\ to\ simplify[/tex]
