Select the correct answer.

Charlie wants to make a one-time investment into an account that earns [tex]6\%[/tex] interest compounded semiannually. To earn [tex]\$338,893[/tex] after 26 years, approximately how much money must he invest?

[tex]S = P \left(1 + \frac{r}{m}\right)^{mt}[/tex]

A. [tex]\$74,492.08[/tex]
B. [tex]\$217,239.10[/tex]
C. [tex]\$72,866.33[/tex]
D. [tex]\$528,673.08[/tex]



Answer :

To solve this problem, we need to determine the present value of an investment that will grow to [tex]$338,893 after 26 years with a 6% interest rate compounded semiannually. The formula for compound interest is given by: \[ S = P \left(1 + \frac{r}{m}\right)^{mt} \] where: - \( S \) is the future value ($[/tex]338,893)
- [tex]\( P \)[/tex] is the present value (the amount to be invested)
- [tex]\( r \)[/tex] is the annual interest rate (0.06 for 6%)
- [tex]\( m \)[/tex] is the number of times interest is compounded per year (2 for semiannually)
- [tex]\( t \)[/tex] is the number of years the money is invested (26)

We need to solve for [tex]\( P \)[/tex]. Rearrange the formula to solve for the present value [tex]\( P \)[/tex]:

[tex]\[ P = \frac{S}{\left(1 + \frac{r}{m}\right)^{mt}} \][/tex]

Now, substitute the known values into the equation:

[tex]\[ P = \frac{338,893}{\left(1 + \frac{0.06}{2}\right)^{2 \times 26}} \][/tex]

Calculate the term inside the parentheses first:

[tex]\[ \left(1 + \frac{0.06}{2}\right) = 1.03 \][/tex]

Next, calculate the exponent:

[tex]\[ 2 \times 26 = 52 \][/tex]

Now, raise the term inside the parentheses to the exponent:

[tex]\[ 1.03^{52} \approx 4.650791682 \][/tex]

Finally, divide the future value by this result to find the present value:

[tex]\[ P = \frac{338,893}{4.650791682} \approx 72,866.33 \][/tex]

Therefore, the correct answer is:

C. [tex]\(\$ 72,866.33\)[/tex]