The equation for exponential growth is A = P(1 + r)^n where A is the total money(interest), P is the principal, r is the rate(compound interest rate) and n is the amount of time. If you look closely and read carefully, you will find out that the principle is $15000. The rate is 0.0325(converted into decimal) and the time is 13 years. If you plug in all of this, you should get A = 15000(1.0325)^13, and A will equal approximately 22733.28$.
