Answer:
Vf = Vi*(1 + 0.00247n)
Explanation:
The interest rate can be converted from anual to monthly by the equation:
(1 + im)¹² = 1 + iy, where im is the interest rate per monthly and iy the interest rate per year:
(1 + im)¹² = 1 + 0.03
1+ im =

1+ im = 1.00247
im = 0.00247 = 0.247%
The final amount (Vf) can be calculated knowing the initial amount (Vi):
Vf = Vi*(1 + im*n), where n is the number of monthes:
Vf = Vi*(1 + 0.00247n)