To find the volume of a cube, you can use the formula:
\[ \text{Volume} = \text{side length}^3 \]
Given the side length of the cube is \(1.5\) in., we calculate the volume as follows:
\[ \text{Volume} = (1.5)^3 = 1.5 \times 1.5 \times 1.5 \]
Calculating step by step:
- \(1.5 \times 1.5 = 2.25\)
- \(2.25 \times 1.5 = 3.375\)
Thus, the volume of the cube is \(3.375\) in³.
Rounding to the nearest thousandth, the final answer is:
\[ \boxed{3.375} \text{ in}^3 \]