To find the percentage of shoes that are rejected, you can use the formula:
\[ \text{Percentage rejected} = \left( \frac{\text{Number rejected}}{\text{Total number}} \right) \times 100 \]
In this case, the factory rejects 3 pairs out of every 200 pairs. So, you can calculate it as follows:
\[ \text{Percentage rejected} = \left( \frac{3}{200} \right) \times 100 = 1.5% \]
Therefore, the percentage of shoes that are rejected is 1.5%.