I assume that means 3.5% annual interest.
Each quarter we multiply our money by [tex]1 + \dfrac{0.035}{4}[/tex]
Eight years is 32 quarters.
So after eight years we have
[tex]A = 4000\left( 1 + \dfrac{0.035}{4} \right)^{32} = \$5286.08[/tex]
That's compared to $5120, principal plus simple interest of just 8(3.5%)=28% of 4000.
Answer: $5286.08
