As of the date of this posting, Test #3 is only about a week and a half away. Generally students think of the probability portion of the class as the most challenging intellectually. The reason is that you don't generally have a cut and dried recipe to follow. The main brainwork is in figuring out a workable approach to each problem.
So allow plenty of time to digest Part 5 of the course. Part 5 is all that is covered on Test #3, but remember that Part 5 relies heavily on the counting techniques learned in Part 4. So there will likely be some things in Part 4 you need to review also.
In any case, try to finish your Part 5 homework assignments as early as possible. That will leave you time to review the adequately for the test.