Final answer:
Cable lube can reduce friction by up to 50%, but the actual reduction may vary. This reduction assists in easier cable installations and protects the cable during pulling. The question mentioned on constantan wire resistance is distinct and not directly related to the cable lube question.
Step-by-step explanation:
To answer the student’s question directly, cable lube can reduce the friction between the cable and duct walls by up to 50%. However, this value may vary depending on the specific type of cable lube, the condition of the cable, and the environment in which it’s being used. Cable lube is important because it ensures that cables can be pulled through conduits more easily, protecting the cable’s integrity and making the installation process more efficient. It’s worth noting that while the percentage provided answers the student’s question, the original question they referred to about the resistance of a constantan wire at 20.0°C is related but requires additional information to answer accurately.