A. You ride your bike along a straight road for a distance d at a constant speed of 13.0 mi/hr and then for another distance 2d along the same straight road at a different constant speed. The average speed for the total trip is 15.0 mi/hr. Determine your constant speed during the second part of the trip. b. Suppose you start the trip by riding in the wrong direction (with the same constant speed as above for the first part of the trip) and after traveling a distance d (in the wrong direction) you realize your mistake. If you then ride to the correct destination with a constant speed, what must this speed be in order for the time for the total trip tb for case (b) to be 1.60ta, where ta is the time for the total trip in part (a). (Enter your answer to at least one decimal place.)