Cd Investment
1. **State the problem:**
Bob invests 1100 for 3 years at an annual interest rate of 1.28% compounded daily. We need to find:
(a) The future value in Bob's account after 3 years.
(b) The amount of interest earned after 3 years.
2. **Identify the formula:**
For compound interest compounded daily, the formula is:
$$ A = P\left(1 + \frac{r}{n}\right)^{nt} $$
where:
- $A$ is the amount after time $t$
- $P = 1100$ is the principal
- $r = 0.0128$ (1.28% as a decimal) is the annual interest rate
- $n = 365$ is the number of compounding periods per year (daily)
- $t = 3$ years is the time
3. **Calculate the amount $A$: **
Plug values into the formula:
$$ A = 1100 \left(1 + \frac{0.0128}{365}\right)^{365 \times 3} $$
Calculate inside the parenthesis:
$$ 1 + \frac{0.0128}{365} = 1 + 0.00003506849315 = 1.00003506849315 $$
Calculate the exponent:
$$ 365 \times 3 = 1095 $$
Now compute:
$$ A = 1100 \times (1.00003506849315)^{1095} $$
Calculate the power:
$$ (1.00003506849315)^{1095} \approx e^{1095 \times 0.00003506849315} = e^{0.038385} \approx 1.039153 $$
So:
$$ A \approx 1100 \times 1.039153 = 1143.0683 $$
Round to nearest cent:
$$ A \approx 1143.07 $$
4. **Calculate interest earned:**
Interest $I = A - P$
$$ I = 1143.07 - 1100 = 43.07 $$
Final answers:
- (a) Future value is $1143.07$
- (b) Interest earned is $43.07$