To calculate the planting density, you need to divide the total number of trees by the total area in acres.
Given:
- Total number of trees = 1,200
- Total area = 4 acres
The planting density can be calculated as follows:
\[ \text{Planting Density} = \frac{\text{Total number of trees}}{\text{Total area in acres}} = \frac{1,200 \text{ trees}}{4 \text{ acres}} = 300 \text{ trees per acre} \]
Therefore, the planting density is 300 trees per acre.