We have to calculate the annual interest rate.
We know:
• Future value (FV): 35,349.62
,
• Present value (PV): 6,000
,
• Period: (n): 15 years
,
• Number of subperiods (m): 4 periods per year (quarterly)
We can relate this values with the equation:

We can replace with the known values and calculate r as:
![\begin{gathered} 35349.62=6000(1+(r)/(4))^(15*4) \\ (35349.62)/(6000)=(1+(r)/(4))^(60) \\ \sqrt[60]{5.89160}=1+(r)/(4) \\ 1.03-1=(r)/(4) \\ 0.03=(r)/(4) \\ r=4*0.03 \\ r=0.12 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/rivvxe35g1toceqo3lp1vgjin9mjrrpygr.png)
The annual rate is r = 0.12, which expressed in percentage corresponds to 12%.
Answer: the annual rate is 12%