Solution
Using the compound interest formula
[tex]A=P(1+\frac{r}{100})^n[/tex]Where
A= Amount due
P= Principal
r=rate per annum
n= number of years
[tex]\begin{gathered} P(1+\frac{r}{100})^n\ge A \\ \\ 39000(1+0.06)^n\ge55000 \\ \\ 1.06^{^n}\ge1.410 \\ \\ n\ge\frac{\ln1.410}{\ln1.06} \\ \\ n\ge5.9 \end{gathered}[/tex]The amount due will reach $55,000 or more after 6 years