An investment banker is responsible for investing a customer's money into the highest interest-earning account. The banker has the following options for the customer's investment:

\begin{tabular}{|l|l|}
\hline
Account A: & Account B: \\
\hline
Interest rate [tex]$= 8\%$[/tex] & Interest rate [tex]$= 7\%$[/tex] \\
Term of investment [tex]$= 8$[/tex] years & Term of investment [tex]$= 10$[/tex] years \\
\hline
Interest compounded annually & Interest compounded continuously \\
\hline
\end{tabular}

Which account, A or B, will earn the customer the greatest amount of interest on a [tex]$\$[/tex]50,000$ investment? Include all of your calculations in your final answer.



Answer :

Let's solve this problem step-by-step:

### Account A:

1. Initial investment (P): [tex]$50,000 2. Annual interest rate (r): 8% or 0.08 3. Term of investment (t): 8 years 4. Compounding frequency (n): 1 time per year (since interest is compounded annually) To calculate the final amount in Account A, we will use the compound interest formula: \[ A = P \left( 1 + \frac{r}{n} \right)^{nt} \] Plugging in the values: \[ A = 50000 \left( 1 + \frac{0.08}{1} \right)^{1 \times 8} \] \[ A = 50000 (1 + 0.08)^8 \] \[ A = 50000 (1.08)^8 \] Performing the calculation: \[ (1.08)^8 \approx 1.85093 \] \[ A \approx 50000 \times 1.85093 \] \[ A \approx 92546.51 \] So, the final amount in Account A after 8 years is approximately \$[/tex]92,546.51.

### Account B:

1. Initial investment (P): [tex]$50,000 2. Annual interest rate (r): 7% or 0.07 3. Term of investment (t): 10 years To calculate the final amount in Account B, we will use the formula for continuous compounding: \[ A = Pe^{rt} \] Plugging in the values: \[ A = 50000 \times e^{0.07 \times 10} \] \[ A = 50000 \times e^{0.7} \] We know that \( e^{0.7} \approx 2.01424 \): \[ A \approx 50000 \times 2.01424 \] \[ A \approx 100687.64 \] So, the final amount in Account B after 10 years is approximately \$[/tex]100,687.64.

### Conclusion:
Comparing the final amounts:
- Account A: \[tex]$92,546.51 - Account B: \$[/tex]100,687.64

The account that earns the greatest amount of interest is Account B. Therefore, the best decision for the customer is to invest in Account B.