The volume \( V \) of a cube can be calculated using the formula:
\[ V = s^3 \]
where \( s \) is the length of a side of the cube.
Given that the side length \( s = 1.5 , \text{in} \), we can calculate the volume as follows:
\[ V = (1.5)^3 = 1.5 \times 1.5 \times 1.5 \] \[ 1.5 \times 1.5 = 2.25 \] \[ 2.25 \times 1.5 = 3.375 \]
Thus, the volume of the cube is:
\[ V = 3.375 , \text{in}^3 \]
Rounding to the nearest thousandth, the final answer is:
\[ \boxed{3.375} \]