Final answer:
The top guardrail must be located at a height of 42 inches, or 1.07 meters, from the walking or working surface to provide adequate fall protection according to safety standards like those of OSHA.
Step-by-step explanation:
The question you're asking relates to safety regulations in a work environment, specifically focusing on the requirements for a guardrail on a walking or working surface.
According to safety standards, such as those set by the Occupational Safety and Health Administration (OSHA), the top guardrail must typically be located at a height of 42 inches (or 1.07 meters) from the walking or working surface. This height ensures a barrier that protects workers from falling off an elevated surface.
The top guardrail must be located at a height of 1.715 m from the walking/working surface. This information is provided in the reference given, which specifies the height of the mirror as precisely one-half the height of the person. The mirror height is 0.890 m.