Final answer:
The damping ratio for a damped spring-mass system cannot be determined without the number of oscillations.
Step-by-step explanation:
The damping ratio for a damped spring-mass system can be calculated using the equation:
ζ = ln(Ai/A_f) / (2πn)
Where ζ is the damping ratio, Ai is the initial amplitude, A_f is the final amplitude, and n is the number of oscillations.
In this case, the initial amplitude is xo and the final amplitude is xo/2. Since the number of oscillations is not given, we cannot calculate the damping ratio.