[tex]p\%=\dfrac{p}{100}\\\\4\%=\dfrac{4}{100}=0.04\\\\\text{Therefore the equation is:}\\\\\boxed{y=3000(1+0.04)^n}[/tex]
Why?
4% per year.
100% + 4% = 1 + 0.04
after the first year
[tex]y=3000(1+0.04)[/tex]
after the second year
[tex]y=3000(1+0.04)(1+0.04)=3000(1+0.04)^2[/tex]
after the third year
[tex]y=3000(1+0.04)^2(1+0.04)=3000(1+0.04)^3[/tex]
. . .
after the nth year
[tex]y=3000(1+0.04)^n[/tex]