Teresa has a copy of her school's student directory on her desk.
Students whose last names start with the letters A to F occupy the first6 pages of the book.
Students whose last names start with the letters G to M occupy the next3 pages of the book.
Students whose last names start with the letters N to R occupy the following 11 pages of the book.
Students whose last names start with the letters S to Z occupy the final10 pages of the book.
If she opens up the directory and picks out a student at random, what is the probability that this student's last name begins with a letter from the first half of the alphabet?
