Final answer:
The purpose of the left-most lane on a road with three or more lanes is to provide a passing lane for faster-moving vehicles.
Step-by-step explanation:
The purpose of the left-most lane on a road with three or more lanes traveling in the same direction is to provide a passing lane for faster-moving vehicles. This lane is typically used by drivers who want to overtake slower vehicles in the middle or right lanes. When driving in the left-most lane, it is important to maintain a consistent speed and move back to the middle or right lane once the overtaking maneuver is complete.