To find what percent of the park is the picnic area, you can use the formula:
\[ \text{Percent} = \left(\frac{\text{Area of picnic area}}{\text{Area of entire park}}\right) \times 100 \]
Given:
- Area of the picnic area = 100 square in
- Area of the entire park = 400 square in
Plugging these numbers into the formula:
\[ \text{Percent} = \left(\frac{100}{400}\right) \times 100 = 25% \]
Thus, the picnic area is 25% of the park.