heather received a $2100 bonus. she decided to invest it in a 2 - year certificate of deposit (cd) with an…

Explanation:

Step1: Identify the compound - interest formula

The compound - interest formula is $A = P(1+\frac{r}{n})^{nt}$, where $P$ is the principal amount, $r$ is the annual interest rate (in decimal form), $n$ is the number of times interest is compounded per year, and $t$ is the number of years. Here, $P=$2100$, $r = 0.0121$, $n = 12$ (compounded monthly), and $t = 2$.

Step2: Calculate the value of $(1+\frac{r}{n})$

$\frac{r}{n}=\frac{0.0121}{12}\approx0.00100833$, and $1+\frac{r}{n}=1 + 0.00100833=1.00100833$.

Step3: Calculate the value of $nt$

$nt=12\times2 = 24$.

Step4: Calculate the future value $A$

$A = 2100\times(1.00100833)^{24}$. Using a calculator, $(1.00100833)^{24}\approx1.024427$. So, $A = 2100\times1.024427=$2151.2967\approx$2151.30$.

Step5: Calculate the interest earned

The interest earned $I=A - P$. So, $I = 2151.30−2100=$51.30$.

Answer:

(a) $$2151.30$ (b) $$51.30$