1. **State the problem:** XYZ Company bought a machine for 50000 and profits start at 7876 in March, increasing by 2% each month. We want to find the month when total profits equal or exceed 50000.
2. **Define variables:** Let $P_0 = 7876$ be the profit in March.
3. **Monthly profit formula:** Each month profit increases by 2%, so profit in month $n$ (starting from March as month 0) is:
$$P_n = P_0 \times (1.02)^n$$
4. **Total profit after $n$ months:** Sum of a geometric series:
$$S_n = P_0 \times \frac{(1.02)^{n+1} - 1}{1.02 - 1} = 7876 \times \frac{(1.02)^{n+1} - 1}{0.02}$$
5. **Find $n$ such that $S_n \geq 50000$:**
$$7876 \times \frac{(1.02)^{n+1} - 1}{0.02} \geq 50000$$
6. **Simplify inequality:**
$$\frac{(1.02)^{n+1} - 1}{0.02} \geq \frac{50000}{7876} \approx 6.35$$
7. Multiply both sides by 0.02:
$$(1.02)^{n+1} - 1 \geq 0.127$$
8. Add 1:
$$(1.02)^{n+1} \geq 1.127$$
9. Take natural logarithm:
$$(n+1) \ln(1.02) \geq \ln(1.127)$$
10. Calculate values:
$$\ln(1.02) \approx 0.0198, \quad \ln(1.127) \approx 0.1197$$
11. Solve for $n$:
$$n+1 \geq \frac{0.1197}{0.0198} \approx 6.05$$
$$n \geq 5.05$$
12. Since $n$ counts months after March (March is $n=0$), the machine is paid off after 6 months (rounding up).
13. **Months:**
- March: $n=0$
- April: $n=1$
- May: $n=2$
- June: $n=3$
- July: $n=4$
- August: $n=5$
- September: $n=6$
14. Therefore, the machine is fully paid off in **September**.
**Final answer:** September
Profit Payoff
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