The area of the scale model of a garden is 15 square feet. The scale model is enlarged by a scale factor of 3 to create the actual garden. Which expression finds the area of the actual garden?

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. \(15 \times 3^2\)**.