The equation, [tex]$A=P\left(1+\frac{0.054}{2}\right)^{2t}$[/tex], represents the amount of money earned on a compound interest savings account with an annual interest rate of 5.4% compounded semiannually. If the initial investment is [tex]\$ 3,000[/tex], determine the amount in the account after 15 years. Round the answer to the nearest hundredths place.

A. [tex]\$ 3,164.19[/tex]
B. [tex]\$ 6,671.67[/tex]
C. [tex]\$ 4,473.81[/tex]
D. [tex]\$ 14,532.47[/tex]



Answer :

To determine the amount in the account after 15 years, we will use the compound interest formula:

[tex]\[ A = P \left(1 + \frac{r}{n}\right)^{nt} \][/tex]

where:
- [tex]\( P \)[/tex] is the initial investment (principal)
- [tex]\( r \)[/tex] is the annual interest rate (expressed as a decimal)
- [tex]\( n \)[/tex] is the number of times the interest is compounded per year
- [tex]\( t \)[/tex] is the number of years
- [tex]\( A \)[/tex] is the amount of money accumulated after [tex]\( t \)[/tex] years, including interest

Given:
- [tex]\( P = 3000 \)[/tex]
- [tex]\( r = 0.054 \)[/tex] (since 5.4% as a decimal is 0.054)
- [tex]\( n = 2 \)[/tex] (since the interest is compounded semiannually)
- [tex]\( t = 15 \)[/tex]

First, we substitute the given values into the formula:

[tex]\[ A = 3000 \left(1 + \frac{0.054}{2}\right)^{2 \cdot 15} \][/tex]

Next, we simplify the expression inside the parentheses:

[tex]\[ 1 + \frac{0.054}{2} = 1 + 0.027 = 1.027 \][/tex]

Then, we calculate the exponent:

[tex]\[ 2 \cdot 15 = 30 \][/tex]

Now, we have:

[tex]\[ A = 3000 \left(1.027\right)^{30} \][/tex]

Finally, we compute the value of [tex]\(\left(1.027\right)^{30}\)[/tex] and multiply by 3000 to find the amount [tex]\( A \)[/tex].

[tex]\[ A \approx 3000 \times 2.22389 \approx 6671.67 \][/tex]

Therefore, the amount in the account after 15 years, rounded to the nearest hundredths place, is:

[tex]\[ \$ 6671.67 \][/tex]

The correct answer is:
[tex]\[ \boxed{\$ 6671.67} \][/tex]