The maximum shear stress \( \tau_{\text{max}} \) in a rectangular beam subjected to transverse loading occurs at the neutral axis (the middle of the beam). The average shear stress \( \tau_{\text{avg}} \) is the total shear force divided by the cross-sectional area of the beam.
For a rectangular cross-section, the relationship between the maximum and average shear stress is given by the formula:
\[
\frac{\tau_{\text{max}}}{\tau_{\text{avg}}} = \frac{3}{2} = 1.5.
\]
Thus, the ratio of the maximum shear stress to the average shear stress is 1.5, and the correct answer is \( (A) 1.50 \).
Final Answer: 1.50