1. **State the problem:**
We have two salary progressions: Helen's salary is constant at $70000$ each year, and Jane's salary starts at $70000$ and grows exponentially by $3\%$ each year, modeled by $$J_n = 70000 \times 1.03^{n-1}$$ where $n$ is the year number.
2. **Understand the formulas:**
- Helen's salary each year: $$H_n = 70000$$ (constant)
- Jane's salary each year: $$J_n = 70000 \times 1.03^{n-1}$$ (exponential growth)
3. **To solve questions about these salaries, typical tasks include:**
- Finding the salary in a specific year $n$.
- Comparing salaries after $n$ years.
- Finding when Jane's salary surpasses Helen's.
4. **Example: Find Jane's salary in year 5.**
Use the formula:
$$J_5 = 70000 \times 1.03^{5-1} = 70000 \times 1.03^4$$
Calculate:
$$1.03^4 = 1.1255$$ (approx)
So,
$$J_5 = 70000 \times 1.1255 = 78785$$ (approx)
5. **Example: When does Jane's salary exceed Helen's?**
Set:
$$J_n > H_n$$
$$70000 \times 1.03^{n-1} > 70000$$
Divide both sides by 70000:
$$\cancel{70000} \times 1.03^{n-1} > \cancel{70000}$$
$$1.03^{n-1} > 1$$
Since $1.03^{n-1}$ is increasing, solve:
$$n-1 > 0 \implies n > 1$$
So Jane's salary surpasses Helen's starting from year 2.
6. **Summary:**
- Use Helen's constant salary formula for any year.
- Use Jane's exponential formula to find salary for any year.
- Compare by setting inequalities and solving for $n$.
This approach helps solve any related questions about these salaries.
Salary Growth 2B14E2
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