The number of cars in a small colony increased from 500 to 600 in a year. Find the percentage increase.

Answer

To find the percentage increase in the number of cars in the colony, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Initial and Final Values**:
- Initial number of cars = 500
- Final number of cars = 600

2. **Calculate the Increase in Number of Cars**:
- Increase = Final number of cars - Initial number of cars
- Increase = 600 - 500 = 100

3. **Use the Percentage Increase Formula**:
- The formula for percentage increase is:
\[ \text{Percentage Increase} = \left( \frac{\text{Increase}}{\text{Initial Value}} \right) \times 100 \]

4. **Substitute the Values into the Formula**:
- Substitute the increase and the initial value into the formula:
\[ \text{Percentage Increase} = \left( \frac{100}{500} \right) \times 100 \]

5. **Calculate the Percentage**:
- Simplify the fraction:
\[ \frac{100}{500} = \frac{1}{5} \]
- Now multiply by 100:
\[ \text{Percentage Increase} = \frac{1}{5} \times 100 = 20 \]

6. **Final Answer**:
- The percentage increase in the number of cars is **20%**.