Final answer:
You must signal for at least 100 feet on four-lane highways with a speed limit over 40 mph before changing lanes or turning.
Step-by-step explanation:
On four-lane highways, where the posted speed limit is more than 40 mph, you must signal for a sufficient distance to give a warning to other drivers before changing lanes or making a turn. Typically, the appropriate distance to signal in advance is at least 100 feet before you make your move. This ensures that other highway users are aware of your intentions and can adjust their driving accordingly for safety. The exact signaling distance may vary depending on state laws, so it's important to consult your local driving regulations. Remember, signaling is not only about following the law; it's also about ensuring the safety of everyone on the road.
On four-lane highways, where the posted speed limit is more than 40 m.p.h., you must signal for lane changes or turns.