In this question, we want to know how much will be in the account after 3 years. Thus, we need to find an equation and since it's an exponential growth, we use the formula
A(t)=a(1+r)t. We know that Katinka's initial deposit was $2000, so a=2000. Further, the rate is r=0.04 since 4%=0.04.A(t)=2000(1+0.04)t
We can substitute 3 for t, since it's 3 years, in our equation and solve for A(t).