Freddy is sailing near a buoy. Freddy starts from a point 3 miles EAST and 2a miles NORTH of the buoy. Freddy then sails in a straight line toward a point 4 miles due SOUTH of the buoy. When Freddy reaches the point closet to the buoy on this course, Freddy changes direction and sails due WEST for 10 miles. Freddy sails at a constant speed 7 miles per hour.

For what length of time is Freddy within 3 miles of the buoy?