(Compound Interest and Geometric Sequences LC)

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, determine the amount in the account after 15 years. Round the answer to the nearest hundredth place.

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



Answer :

To determine the amount of money in a compound interest savings account after 15 years, we can follow these steps:

1. Identify the variables in the compound interest formula:
- Initial investment (principal), [tex]\( P \)[/tex]: \[tex]$3000 - Annual interest rate, \( r \): 5.4% or 0.054 in decimal form - Number of times interest is compounded per year, \( n \): 2 (semiannually) - Number of years the money is invested, \( t \): 15 2. Use the compound interest formula: \[ A = P \left( 1 + \frac{r}{n} \right)^{nt} \] Here, \( A \) is the amount of money accumulated after \( t \) years, including interest. 3. Plug in the values into the formula: \[ A = 3000 \left( 1 + \frac{0.054}{2} \right)^{2 \times 15} \] 4. Calculate the value inside the parenthesis first: \[ 1 + \frac{0.054}{2} = 1 + 0.027 = 1.027 \] 5. Raise this value to the power of \( 2 \times 15 = 30 \): \[ 1.027^{30} \] 6. Multiply the result by the principal \( P \): \[ A = 3000 \times 1.027^{30} \] 7. Perform the calculations to determine \( A \): - Calculate \( 1.027^{30} \approx 2.22389 \) - Multiply this by 3000: \[ 3000 \times 2.22389 = 6671.670091129403 \] 8. Round the result to the nearest hundredths place: \[ 6671.670091129403 \approx 6671.67 \] Therefore, the amount of money in the account after 15 years, rounded to the nearest hundredths place, is $[/tex]\[tex]$ 6,671.67$[/tex].

Among the given options:
- [tex]$3,164.19$[/tex]
- [tex]$\$[/tex] 6,671.67[tex]$ - $[/tex]\[tex]$ 4,473.81$[/tex]
- [tex]$\$[/tex] 14,532.47[tex]$ The correct answer is \$[/tex] 6,671.67.