Loan Compound
1. **State the problem:** We have a loan of 34000 with an annual interest rate of 4.25% compounded annually. We want to find the smallest whole number of years $t$ such that the amount due is at least 63000.
2. **Formula used:** The compound interest formula is
$$A = P\left(1 + \frac{r}{n}\right)^{nt}$$
where:
- $A$ is the amount after time $t$,
- $P$ is the principal (initial amount),
- $r$ is the annual interest rate (decimal),
- $n$ is the number of times interest is compounded per year,
- $t$ is the number of years.
Since interest is compounded annually, $n=1$, so the formula simplifies to
$$A = P(1 + r)^t$$
3. **Plug in known values:**
$$63000 \leq 34000(1 + 0.0425)^t$$
4. **Isolate $(1 + 0.0425)^t$:**
$$\frac{63000}{34000} \leq (1.0425)^t$$
$$1.852941176 \leq (1.0425)^t$$
5. **Take natural logarithm on both sides:**
$$\ln(1.852941176) \leq \ln((1.0425)^t)$$
$$\ln(1.852941176) \leq t \ln(1.0425)$$
6. **Solve for $t$:**
$$t \geq \frac{\ln(1.852941176)}{\ln(1.0425)}$$
Calculate the values:
$$\ln(1.852941176) \approx 0.6162$$
$$\ln(1.0425) \approx 0.0416$$
$$t \geq \frac{0.6162}{0.0416} \approx 14.81$$
7. **Interpretation:** Since $t$ must be a whole number and the amount must reach or exceed 63000, we round up to the next whole number:
$$t = 15$$
**Final answer:** The amount due will reach 63000 or more after **15 years**.