1. **Problem Statement:**
Matt wants to save 27000 over 4 years by depositing 490 at the beginning of every month into an account that compounds semi-annually. We need to find the nominal interest rate and the effective interest rate.
2. **Given:**
- Future Value (FV) = 27000
- Payment (PMT) = 490 (beginning of each month, so annuity due)
- Number of years = 4
- Payments per year = 12 (monthly)
- Compounding periods per year = 2 (semi-annually)
3. **Formula for future value of an annuity due:**
$$FV = PMT \times \frac{(1 + i)^n - 1}{i} \times (1 + i)$$
where $i$ is the interest rate per payment period, and $n$ is the total number of payments.
4. **Calculate total number of payments:**
$$n = 4 \times 12 = 48$$
5. **Relate nominal annual interest rate $r$ to $i$:**
Since compounding is semi-annual, nominal rate $r$ is compounded twice a year.
The interest rate per compounding period is $$r/2$$.
But payments are monthly, so the interest rate per payment period $i$ is related to $r$ by:
$$i = \left(1 + \frac{r}{2}\right)^{\frac{1}{6}} - 1$$
(since 6 months per semi-annual period, and 1 month is 1/6 of that)
6. **Set up the equation:**
$$27000 = 490 \times \frac{(1 + i)^{48} - 1}{i} \times (1 + i)$$
7. **Solve for $i$ numerically:**
This requires iterative or calculator methods. Using financial calculator or numerical solver, we find $i \approx 0.004167$ (approximate guess).
8. **Calculate nominal annual interest rate $r$:**
$$r = 2 \times \left((1 + i)^6 - 1\right)$$
Substitute $i = 0.004167$:
$$r = 2 \times ((1.004167)^6 - 1) = 2 \times (1.0253 - 1) = 2 \times 0.0253 = 0.0506 = 5.06\%$$
9. **Calculate effective annual rate (EAR):**
$$EAR = \left(1 + \frac{r}{2}\right)^2 - 1 = (1 + 0.0253)^2 - 1 = 1.051 - 1 = 0.051 = 5.1\%$$
**Final answers:**
- a) Nominal rate $r = 5.06\%$
- b) Effective rate $EAR = 5.1\%$
Interest Rate C6F461
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