To find the area of the actual garden when the scale model is enlarged by a scale factor of 3, you need to square the scale factor since area is two-dimensional.
Given:
- Area of the scale model = 15 square feet
- Scale factor = 3
The area of the actual garden can be found using the following formula:
\[ \text{Area of actual garden} = \text{Area of scale model} \times \text{(scale factor)}^2 \]
Substituting the values we have:
\[ \text{Area of actual garden} = 15 \times 3^2 \]
Calculating \(3^2\):
\[ 3^2 = 9 \]
Then, the area of the actual garden is:
\[ 15 \times 9 \]
So, the correct expression that represents the area of the actual garden is:
4. \(15 \times 3^2\).