Answer:
16 1/4 years
Step-by-step explanation:
Assuming interest is compounded annually, the account balance (A) after t years will be ...
A = P(1 +r)^t
3200 = 1700·1.0397^t
log(3200) = log(1700) +t·log(1.0397)
t = (log(3200) -log(1700))/log(1.0397) ≈ 16.247
The account will reach a balance of $3200 after about 16 1/4 years.
___
You may be asked to round your answer to the nearest integer or tenth. We leave that exercise to the student.