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Determine the ratio of the population of town X (call it [tex]P_X[/tex]) to the population of town Y (call it [tex]P_Y[/tex]) at the beginning of 2010.

For each of the three years from 2010 to 2012:
- The population of town X decreased by 8% per year.
- The population of town Y increased by 12% per year.

At the end of 2012, the populations of these two towns were equal.

Calculate the ratio [tex]\frac{P_X}{P_Y}[/tex] at the beginning of 2010.


Sagot :

Certainly! Let's solve this problem step-by-step:

### Problem Analysis
1. Town X: Decreases by 8% per year.
2. Town Y: Increases by 12% per year.
3. At the end of 2012, the populations of the two towns are equal.
4. We need to determine the ratio of the population of town X to the population of town Y at the beginning of 2010.

### Step-by-Step Solution
1. Initial Populations:
- Let the population of town X at the beginning of 2010 be [tex]\( P_X \)[/tex].
- Let the population of town Y at the beginning of 2010 be [tex]\( P_Y \)[/tex].

2. Population Changes Over Three Years:
- Town X decreases by 8% each year, which means it retains 92% [tex]\((100\% - 8\% = 92\%)\)[/tex] of its population each year.
- Town Y increases by 12% each year, which means it becomes 112% [tex]\((100\% + 12\% = 112\%)\)[/tex] of its population each year.

3. Population Formulas After Three Years:
- For town X:
[tex]\[ P_{X\_2012} = P_X \times 0.92^3 \][/tex]
- For town Y:
[tex]\[ P_{Y\_2012} = P_Y \times 1.12^3 \][/tex]

4. Equality at the End of 2012:
- At the end of 2012, the populations are equal:
[tex]\[ P_X \times 0.92^3 = P_Y \times 1.12^3 \][/tex]

5. Ratio of Initial Populations:
- To find the ratio [tex]\( \frac{P_X}{P_Y} \)[/tex], we rearrange the equation:
[tex]\[ \frac{P_X}{P_Y} = \frac{1.12^3}{0.92^3} \][/tex]

6. Calculating the Ratio:
- The calculation yields:
[tex]\[ \frac{1.12^3}{0.92^3} \approx 1.804 \][/tex]

### Conclusion
The ratio of the population of town X to the population of town Y at the beginning of 2010 is approximately [tex]\( 1.804 \)[/tex].

Hence, if the population of town Y at the beginning of 2010 was one unit, the population of town X at the same time would be approximately 1.804 units.