Nominal Rate Daily
1. **Problem Statement:** The treasurer wants to change the compounding from semi-annually to daily but keep the same effective interest rate. The current nominal rate is 10.1% compounded semi-annually. We need to find the new nominal rate compounded daily that yields the same effective rate.
2. **Formula for Effective Annual Rate (EAR):**
$$EAR = \left(1 + \frac{r}{n}\right)^n - 1$$
where $r$ is the nominal rate and $n$ is the number of compounding periods per year.
3. **Calculate the current EAR:**
Given $r = 0.101$ (10.1%) and $n = 2$ (semi-annual),
$$EAR = \left(1 + \frac{0.101}{2}\right)^2 - 1 = (1 + 0.0505)^2 - 1 = 1.0505^2 - 1$$
$$= 1.10302525 - 1 = 0.103025$$
So, the effective annual rate is approximately 10.3025%.
4. **Find the new nominal rate $r_{new}$ compounded daily:**
We want the same EAR with $n = 365$ (daily compounding), so
$$0.103025 = \left(1 + \frac{r_{new}}{365}\right)^{365} - 1$$
Add 1 to both sides:
$$1.103025 = \left(1 + \frac{r_{new}}{365}\right)^{365}$$
Take the 365th root:
$$\left(1.103025\right)^{\frac{1}{365}} = 1 + \frac{r_{new}}{365}$$
Calculate the left side:
$$\left(1.103025\right)^{\frac{1}{365}} \approx 1.000269$$
So,
$$1.000269 = 1 + \frac{r_{new}}{365}$$
Subtract 1:
$$0.000269 = \frac{r_{new}}{365}$$
Multiply both sides by 365:
$$r_{new} = 0.000269 \times 365 = 0.098185$$
5. **Convert to percentage and round:**
$$r_{new} = 9.8185\%$$
**Final answer:** The new nominal rate compounded daily should be approximately **9.8185%** to maintain the same effective interest rate.