To find the area of the actual garden after enlarging the scale model by a scale factor of 3, we can use the following relationship:
When an area is scaled by a factor \( k \), the new area becomes \( k^2 \) times the original area.
In this case, the scale factor \( k \) is 3. Therefore, the area of the actual garden can be expressed as:
\[ \text{Area of actual garden} = \text{Area of scale model} \times k^2 = 15 \times 3^2 \]
Calculating \( 3^2 \) gives us 9, so:
\[ \text{Area of actual garden} = 15 \times 9 \]
Thus, the correct expression to find the area of the actual garden is:
15 times 3 squared.