Yes, an observation reported within 10 minutes of the actual time will likely be considered accurate. The concept of proper time involves precision based on an observer's location, but minor height differences have a negligible effect on time measurements.
The question relates to the precision of time observations and the concept of proper time in physics. If an observation is made within 10 minutes of the actual time, it will likely be reported as accurate depending on the context of the observation. For example, reaction time on a stopwatch may affect the precision of timed observations. Similarly, proper time, which is the time measured by an observer at the location of the event, can differ from the time measurements made by other observers depending on their relative velocities and positions.
In the context of the 18th question, while general relativity does suggest that time can run at different rates due to gravity (gravitational time dilation), the difference in time at the top and base of a building would be minuscule, not enough to account for a 5-minute discrepancy. Therefore, the friend's excuse is not scientifically reasonable.
The observation within a 10-minute window would generally be considered acceptable, and proper time must be considered when dealing with high speeds or gravitational fields, but slight height differences in everyday experiences like being on top of a tall building won't significantly affect time measurements.