What are the limitations of using the fundamental counting principle when determining the probability of an outcome

Which fraction below is equivalent to 10/12?

Two friends are reading books. jimmy reads a book with 21,356 words. his friend bob reads a book with one-and-a-half times as many words. which expression represents the number of words bob reads?

Let event a = you roll an even number on the first cube.let event b = you roll a 6 on the second cube.are the events independent or dependent? why?