Final answer:
The distance between the flagman and two yellow lights should be within a reasonable range, typically a few meters or yards.
Step-by-step explanation:
The distance between the flagman and two yellow lights should be determined based on both practical and theoretical considerations. In practical terms, the flagman should be positioned far enough from the yellow lights to ensure visibility without causing discomfort to the eyes of the viewers.
The theoretical limit for resolving two points held at arm's length is approximately 0.8 meters or 2.6 feet. Therefore, based on these factors, the distance between the flagman and two yellow lights should be within a reasonable range, typically a few meters or yards.