Question 441706
{{{8000 = 5000(1 + 0.085/4)^(4t)}}}

{{{8/5 = 1.02125^(4t)}}}

{{{ln(1.6) = 4t*ln(1.02125)}}}

{{{t = ln(1.6)/(4ln(1.02125)) = 5.6}}} years.