It depends on how long. Use this formula to calculate total interest:
i = pv * ((1 + r/n) ^ (n*t) - 1)
where pv = present value (25000), r = annual rate (0.03), n = compounding (12 if monthly), and t = time in years.
For example, for 1 year (t=1),
i = 25000 * ((1 + 0.03/12) ^ (12*1) - 1) = 760.40
For different amounts of time, change t.
Compound 3% per month
