Given:
Interest rate = 2.5% compounded quarterly
Final Amount = $20,000
Time = 15 years
Let's find the amount you should invest in the account.
Here, we are to find the principal amount.
Apply the formula:
![A=P(1+(r)/(n))^(nt)](https://img.qammunity.org/2023/formulas/mathematics/high-school/39foo2gerf9tf1ffk32zwshrn339mz02kv.png)
Where:
A is the final amount = $20,000
r is the rate = 2.5% = 0.025
compound frequency is n. Since it is compounded quarterly, n = 4
t is the time in years = 15 years.
Let's solve for P.
We have:
![\begin{gathered} 20000=P(1+(0.025)/(4))^(4*15) \\ \\ 20000=P(1+0.00625)^(60) \\ \\ 20000=P(1.00625)^(60) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/8w8n005l5ge1lb1qyotcn3e3b437k7aj3w.png)
Solving further:
![20000=P(1.45329)](https://img.qammunity.org/2023/formulas/mathematics/college/4ce9phybft5ezosgvuka4474sflazozid3.png)
Divide both sides by 1.45329:
![\begin{gathered} (20000)/(1.45329)=(P(1.45329))/(1.45329) \\ \\ 13761.87=P \\ \\ P=13761.87 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/wzyf1qjxo4c3muk40jtrp55gx2078uvjxq.png)
Therefore, the amount that should be invested is $13,761.87
ANSWER:
$13,761.87