A = $ value after 15 years
P = principal (initial deposit)
r = annual % rate
n = # of times interest compounds per year
t = # of years the money is invested
Formula:
A = P (1 + r/n)^(nt)
A= $3400(1+ 0.0775/1) ^(1*15)
A= 3400(1.0775)^15
A= 3400(3.0637913274)
A= $10,417 investment after 15 years
Hope this helps! :)