Subjects finance

Interest Rate C6F461

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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 $EAR = 5.1\%$