To find the overall percentage increase over the four years, we can calculate the population after each annual increase, starting from an initial population (let's say 100 for simplicity) and then applying each percentage increase consecutively.
- Initial Population: 100
- First Year (20% increase): \[ \text{Population} = 100 + (20/100) \times 100 = 100 + 20 = 120 \]
- Second Year (25% increase): \[ \text{Population} = 120 + (25/100) \times 120 = 120 + 30 = 150 \]
- Third Year (30% increase): \[ \text{Population} = 150 + (30/100) \times 150 = 150 + 45 = 195 \]
- Fourth Year (10% increase): \[ \text{Population} = 195 + (10/100) \times 195 = 195 + 19.5 = 214.5 \]
Now, we can find the overall percentage increase from the initial population of 100 to the final population of 214.5.
To find the overall percentage increase: \[ \text{Overall Percentage Increase} = \left(\frac{\text{Final Population} - \text{Initial Population}}{\text{Initial Population}}\right) \times 100 \] \[ = \left(\frac{214.5 - 100}{100}\right) \times 100 = \left(\frac{114.5}{100}\right) \times 100 = 114.5% \]
Therefore, the overall percentage increase in the population over the 4 years is 114.5%.