The problem's formulation (three first lines in my copy) is incorrect and incomplete.


The complete and correct formulation 

    - must say that the track is a closed line or a closed path, like circle, or ellipse,
      or oval.

             The problem tries to tell it by saying "clockwise", but in professional formulation,
             it must say it directly, openly and explicitly.


    - must give the LENGTH of the track.


Then we can answer the problems' question: Moving faster than Bob, Alice should cover 
the extra distance equal to the track's length, to catch up Bob for the first time.


Given rates in the problem (4 miles per hour for Alice and 3 miles per hour for Bob)
are irrelevant to the problem's question.


Let me repeat my point again: as worded and printed in the post, the problem
is posed incorrectly and can not be solved.


To be solved, irrelevant data should be ignored and necessary data should be added.


For example, if the track length is 6 miles, then the extra distance, which Alice
should cover to catch up Bob for the first time, is 6 miles.