1. **State the problem:** Amir and Eva each invest 100000 at 7.5% per annum for 5 years. Amir's interest is compounded daily, Eva's annually. We need to find how much more Amir earned than Eva.
2. **Formulas:**
- Compound interest formula: $$A = P \left(1 + \frac{r}{n}\right)^{nt}$$
- Where $A$ is the amount, $P$ is principal, $r$ is annual interest rate (decimal), $n$ is number of compounding periods per year, $t$ is time in years.
3. **Calculate Eva's amount (compounded annually):**
- $P = 100000$, $r = 0.075$, $n = 1$, $t = 5$
- $$A_{Eva} = 100000 \left(1 + \frac{0.075}{1}\right)^{1 \times 5} = 100000 (1.075)^5$$
- Calculate $(1.075)^5$:
$$1.075^5 = 1.43563$$
- So,
$$A_{Eva} = 100000 \times 1.43563 = 143563$$
4. **Calculate Amir's amount (compounded daily):**
- $P = 100000$, $r = 0.075$, $n = 365$, $t = 5$
- $$A_{Amir} = 100000 \left(1 + \frac{0.075}{365}\right)^{365 \times 5} = 100000 \left(1 + 0.00020548\right)^{1825}$$
- Calculate base:
$$1 + 0.00020548 = 1.00020548$$
- Calculate exponent:
$$1.00020548^{1825} = e^{1825 \times \ln(1.00020548)}$$
- Approximate $\ln(1.00020548) \approx 0.00020546$
- So exponent:
$$1825 \times 0.00020546 = 0.3749$$
- Then:
$$e^{0.3749} = 1.4543$$
- Therefore:
$$A_{Amir} = 100000 \times 1.4543 = 145430$$
5. **Calculate difference:**
- $$\text{Difference} = A_{Amir} - A_{Eva} = 145430 - 143563 = 1867$$
6. **Final answer:** Amir earned 1867 more than Eva in 5 years.
Compound Interest 3F6069
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