1. In Exercise 3.7, it states "your job is to paint bookcases...or to leave the bookcase unpainted." "Bookcase" should be changed to "bookcases," because otherwise it makes it seem that only one of the eight bookcases can be unpainted.
  2. This is a small typo in exercise 3.6. The first and second to last sentence refer to drug types as "drugs types" with an unneeded added s after drug.
  3. This is really minor, but the last sentence of Exercise 3.11 is a question, so it should end in a question mark and not a period. Only to keep consistency with the other exercises in chapter 3, in which all questions end with question marks.
  4. I am reposting here, because I realized that I accidentally posted on another page. For Exercise 3.7, it says "Your job is to paint bookcases one of three different colors or to leave the bookcase unpainted. You have eight different bookcases and all of the book cases have a different height. In how many ways can you do your job?" The first error (a barely noticeable one) is the space between "book" and "cases." The second is not really an error, but rather something I found to be superfluous. Because the question doesn't really concern the height of the bookcases, mentioning that the bookcases have a different height isn't really necessary. I believe the issue of height was more important in Exercise 3.9.
  5. There are 2 minor typos in the second to last sentence in exercise 3.9. There should be a "the" in front of "shortest three book cases..." Also, "book cases" should be combined and written as "bookcases." The sentence should then read "If the tallest bookcase is red, then the shortest three bookcases must be painted the same color..."