Final answer:
Kristen will earn approximately $30.25 in interest at the end of one month with a 4.1% annual interest rate compounded monthly. This calculation is based on her $9,000 initial deposit using the compound interest formula.
Step-by-step explanation:
Kristen's interest can be calculated using the formula for compound interest:
![\[ A = P \left(1 + (r)/(n)\right)^(nt) \]](https://img.qammunity.org/2021/formulas/mathematics/high-school/afqdilx2t2c5taxlzn1q6eltry86vq5iqk.png)
where:
-
is the future value of the investment/loan, including interest,
-
is the principal amount (initial deposit),
-
is the annual interest rate (as a decimal),
-
is the number of times that interest is compounded per unit
(time in years), and
-
is the time the money is invested/borrowed for in years.
In this case, Kristen's principal
is $9,000, the annual interest rate
is 4.1%, compounded monthly
, and
is 1/12 since we're calculating for one month.
![\[ A = 9000 \left(1 + (0.041)/(12)\right)^{(12 \cdot (1)/(12))} \]](https://img.qammunity.org/2021/formulas/mathematics/high-school/lkvis2bzbu24xukopl1roxxm9egy1nl0sd.png)
Solving this equation yields the future value after one month, including interest. Subtracting the initial principal gives us the interest earned:
![\[ \text{Interest} = A - P \]](https://img.qammunity.org/2021/formulas/mathematics/high-school/o42ivoiq374uhog5xhnsgbamy1bmqo7ydm.png)
After the calculations, the interest earned is approximately $30.25. This amount represents the interest Kristen will have accrued on her $9,000 deposit after one month, considering the compounded monthly interest rate of 4.1%.