Your Principal, P, is $400. Your interest rate, expressed as a decimal, is 0.03. Here, n is 1, since there is just 1 compounding period per year.
How much would you have after 16 years under such circumstances?
A = Amount = $400(1+0.03)^16. => $400 (1.03)^16 = $400(1.60)
Thus, you would have accumulated $641.88 after 16 years. Sounds like a pretty good deal to me. ;)