Investment Growth 940F61
1. **Problem statement:** We want to find how many years it will take for an investment of 50000 to grow to 60000 with an interest rate of 10% compounded quarterly.
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 investment),
- $r$ is the annual interest rate (decimal),
- $n$ is the number of compounding periods per year,
- $t$ is the time in years.
3. **Given values:**
- $P = 50000$
- $A = 60000$
- $r = 0.10$
- $n = 4$ (quarterly compounding)
4. **Substitute values into the formula:**
$$60000 = 50000 \left(1 + \frac{0.10}{4}\right)^{4t}$$
5. **Simplify inside the parentheses:**
$$60000 = 50000 \left(1 + 0.025\right)^{4t} = 50000 (1.025)^{4t}$$
6. **Divide both sides by 50000:**
$$\frac{60000}{50000} = (1.025)^{4t}$$
$$1.2 = (1.025)^{4t}$$
7. **Take the natural logarithm of both sides:**
$$\ln(1.2) = \ln\left((1.025)^{4t}\right) = 4t \ln(1.025)$$
8. **Solve for $t$:**
$$t = \frac{\ln(1.2)}{4 \ln(1.025)}$$
9. **Calculate the values:**
$$\ln(1.2) \approx 0.182321556$$
$$\ln(1.025) \approx 0.02469261$$
10. **Final calculation:**
$$t = \frac{0.182321556}{4 \times 0.02469261} = \frac{0.182321556}{0.09877044} \approx 1.846$$
**Answer:** It will take approximately **1.85 years** for the investment to grow from 50000 to 60000 with 10% interest compounded quarterly.