Exponentials and Logarithms

Finding the final amount in a word problem on exponential growth or decay:

A principal of $5000 is invested at 5.5% interest, compounded annually. How much will the investment be worth after 14 years?

Use the calculator provided and round your answer to the nearest dollar.



Answer :

To solve the problem of finding how much a principal of [tex]$5000 will be worth after 14 years when it is invested at an annual interest rate of 5.5%, compounded annually, follow these steps: 1. Understand the formula for compound interest: \[ A = P \left(1 + \frac{r}{n}\right)^{nt} \] where: - \( A \) is the amount of money accumulated after \( n \) years, including interest. - \( P \) is the principal amount (the initial amount of money). - \( r \) is the annual interest rate (decimal). - \( n \) is the number of times the interest is compounded per year. - \( t \) is the number of years the money is invested for. Since the interest is compounded annually, \( n = 1 \). 2. Plug in the given values: - \( P = 5000 \) - \( r = 5.5\% = 0.055 \) (conversion from percentage to decimal) - \( n = 1 \) - \( t = 14 \) 3. Substitute the values into the formula: \[ A = 5000 \left(1 + \frac{0.055}{1}\right)^{1 \times 14} \] 4.Simplify the formula: \[ A = 5000 \left(1 + 0.055\right)^{14} \] \[ A = 5000 \left(1.055\right)^{14} \] 5. Calculate the value of \((1.055)^{14}\): \[ (1.055)^{14} \approx 2.11609146 \] 6. Multiply the result by the principal amount ($[/tex]5000):
[tex]\[ A = 5000 \times 2.11609146 \][/tex]
[tex]\[ A \approx 10580.457309184592 \][/tex]

7. Round the result to the nearest dollar:
[tex]\[ A \approx 10580 \][/tex]

So, the investment will be worth approximately $10,580 after 14 years.