1. **State the problem:** We have two towns, A and B, with populations growing exponentially. Town A starts with 4000 people and grows at 8% per year. Town B starts with 5000 people and grows at 6% per year.
2. **Formulas for exponential growth:** The population after $t$ years is given by $$P = P_0 (1 + r)^t$$ where $P_0$ is the initial population and $r$ is the growth rate.
3. **Calculate populations after 5 years:**
- Town A: $$P_A = 4000 \times (1 + 0.08)^5 = 4000 \times 1.08^5$$
- Town B: $$P_B = 5000 \times (1 + 0.06)^5 = 5000 \times 1.06^5$$
4. **Evaluate powers:**
- $$1.08^5 = 1.4693$$ (approx)
- $$1.06^5 = 1.3382$$ (approx)
5. **Calculate populations:**
- $$P_A = 4000 \times 1.4693 = 5877.2$$
- $$P_B = 5000 \times 1.3382 = 6691$$
6. **Compare populations:**
- Town B has more people after 5 years.
- Difference: $$6691 - 5877.2 = 813.8$$ which is less than 1000.
7. **Answer for Part A:** The size of the population in Town B will be greater than that of Town A with a difference less than 1000 people. This corresponds to option C.
8. **Part B: Find when populations are equal:**
Set $$4000 (1.08)^t = 5000 (1.06)^t$$
9. **Divide both sides:**
$$\frac{4000 (1.08)^t}{5000 (1.06)^t} = 1$$
$$\frac{4000}{5000} \times \frac{(1.08)^t}{(1.06)^t} = 1$$
$$\frac{4}{5} \times \left(\frac{1.08}{1.06}\right)^t = 1$$
10. **Isolate exponential term:**
$$\left(\frac{1.08}{1.06}\right)^t = \frac{5}{4} = 1.25$$
11. **Take natural logarithm:**
$$t \ln\left(\frac{1.08}{1.06}\right) = \ln(1.25)$$
12. **Calculate logarithms:**
$$\ln\left(\frac{1.08}{1.06}\right) = \ln(1.0188679) = 0.0187$$
$$\ln(1.25) = 0.2231$$
13. **Solve for $t$:**
$$t = \frac{0.2231}{0.0187} = 11.93$$ years (approx)
14. **Calculate population at $t=11.93$:**
Using Town A's formula:
$$P = 4000 \times 1.08^{11.93}$$
Calculate power:
$$1.08^{11.93} = e^{11.93 \times \ln(1.08)} = e^{11.93 \times 0.07696} = e^{0.918} = 2.504$$
Population:
$$P = 4000 \times 2.504 = 10016$$ (approx)
15. **Answer for Part B:** The populations will be equal at about 10,016 people.
**Final answers:**
- Part A: Option C
- Part B: Approximately 10,016 people
Population Growth Ade1E6
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