A factory kept increasing its output by the same percentage every year. Find the percentage if it is known that the output is doubled in the last two years.

Explanation

To find the percentage increase in output for a factory that doubles its output over two years, we can follow these steps:

### Step-by-Step Solution:

1. **Define the Initial Output:**
Let the initial output of the factory be \( P \).

2. **Define the Percentage Increase:**
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