A small boat is headed for a harbor 30 km directly northwest of its current position when it is suddenly engulfed in heavy fog. The captain maintains a compass bearing of northwest and a speed of 9.8 km/h relative to the water. The fog lifts 3.0 h later and the captain notes that he is now exactly 3.6 km south of the harbor.
(a) What was the average speed of the current during those 3.0 h?
(b) What would its travel time have been if it had followed a straight course?